Use of header syntax elements and adaptation parameter set

ABSTRACT

Systems, methods and apparatus for video processing are described. The video processing may include video encoding, video decoding, or video transcoding. One example method of video processing includes performing a conversion between a video and a bitstream of the video according to a format rule. The format rule specifies that constraints on values of one or more first syntax elements in an adaptation parameter set are defined based on semantics of second syntax elements in a picture header and/or a slice header if a picture or a slice referring to the adaptation parameter set.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/CN2021/086178 filed on Apr. 9, 2021, which claims the priorityto and benefits of International Patent Application No.PCT/CN2020/084295 filed on Apr. 10, 2020. All the aforementioned patentapplications are hereby incorporated by reference in their entireties.

TECHNICAL FIELD

The present disclosure relates to image and video coding and decoding.

BACKGROUND

Digital video accounts for the largest bandwidth use on the internet andother digital communication networks. As the number of connected userdevices capable of receiving and displaying video increases, it isexpected that the bandwidth demand for digital video usage will continueto grow.

SUMMARY

The present disclosure discloses techniques that can be used by videoencoders and decoders for processing coded representation of video usingcontrol information useful for decoding of the coded representation.

In one example aspect, a video processing method is disclosed. Themethod includes performing a conversion between a video having one ormore chroma components, the video comprising one or more video picturescomprising one or more slices and a coded representation of the video,wherein the coded representation conforms to a format rule, wherein theformat rule specifies that a chroma array type field controls aconstraint on a conversion characteristic of chroma used during theconversion.

In another example aspect, another video processing method is disclosed.The method includes performing a conversion between a video comprisingone or more video pictures comprising one or more video regions and acoded representation of the video, wherein the coded representationconforms to a format rule that specifies the include a deblocking modeindicator for a video region indicative of applicability of a deblockingfilter to the video region during the conversion.

In another example aspect, another video processing method is disclosed.The method includes performing a conversion between a video comprisingone or more video pictures comprising one or more video slices and/orone or more video subpictures and a coded representation of the video,wherein the coded representation conforms to a format rule thatspecifies that a flag indicating whether a single slice per subpicturemode is deemed to be enabled for a video picture in case that a picturepartitioning is disabled for the video picture.

In another example aspect, another video processing method is disclosed.The method includes performing a conversion between a video comprisingone or more video pictures comprising one or more video slices and acoded representation of the video, wherein the coded representationconforms to a format rule that specifies that a picture or a slice levelchroma quantization parameter offset is signaled in a picture header ora slice header.

In another example aspect, another video processing method is disclosed.The method includes: performing a conversion between a video comprisingone or more video pictures comprising one or more video slices and acoded representation of the video, wherein the coded representationconforms to a format rule that specifies that a chroma quantizationparameter (QP) table applicable for conversion of a video block of thevideo is derived as an XOR operation between(delta_qp_in_val_minus1[i][j]+1) and delta_qp_diff_val[i][j], whereindelta_qp_in_val_minus1[i][j] specifies a delta value used to derive theinput coordinate of the j-th pivot point of the i-th chroma mappingtable and delta_qp_diff_val[i][j] specifies a delta value used to derivethe output coordinate of the j-th pivot point of the i-th chroma QPmapping table, where i and j are integers.

In another example aspect, another video processing method is disclosed.The method includes performing a conversion between a video and abitstream of the video according to a format rule, and wherein theformat rule specifies that constraints on values of one or more firstsyntax elements in an adaptation parameter set are defined based onsemantics of second syntax elements in a picture header and/or a sliceheader if a picture or a slice referring to the adaptation parameterset.

In another example aspect, another video processing method is disclosed.The method includes performing a conversion between a video and abitstream of the video according to a format rule, and wherein theformat rule specifies that a syntax element specifying whether achroma-related APS (adaptation parameter set) syntax element is presentis included in an APS syntax structure.

In another example aspect, another video processing method is disclosed.The method includes performing a conversion between a video and abitstream of the video according to a format rule, and wherein theformat rule specifies that a constraint on a value of a first syntaxelement indicating a presence of chroma information in an APS(Adaptation Parameter Set) NAL (Network Abstraction Layer) unit is basedon a type of the adaptation parameter set and a second syntax elementindicating a presence of a chroma component in the video.

In another example aspect, another video processing method is disclosed.The method includes performing a conversion between a video and abitstream of the video according to a format rule, and wherein theformat rule specifies that a first syntax element indicating a presenceof a chroma component in the video is constrained depending on a secondsyntax element indicating a presence of chroma information in an APS(Adaptation Parameter Set) NAL (Network Abstraction Layer) unit and/or atype of the APS.

In another example aspect, another video processing method is disclosed.The method includes performing a conversion between a video and abitstream of the video according to a format rule, and wherein theformat rule specifies, responsive to a second syntax element of anadaptation parameter set (APS) indicating a presence of a chromacomponent in the video being greater than a certain value, a value of afirst syntax element of an APS NAL (Network Abstraction Layer) unithaving an APS parameter type equal to LMCS (luma mapping with chromascaling)_APS and an APS identifier equal to information included in apicture header of a picture referring to the APS is constrained to beequal to a certain value.

In another example aspect, another video processing method is disclosed.The method includes performing a conversion between a video and abitstream of the video according to a format rule, and wherein theformat rule specifies how to signal or constrain one or more firstsyntax elements in an adaptation parameter set based on a value of a APS(adaptation parameter set) syntax element specifying an allowance ofpresence of chroma-related syntax elements in an adaptation parameterset.

In another example aspect, another video processing method is disclosed.The method includes performing a conversion between a video and abitstream of the video according to a format rule, and wherein theformat rule specifies that an ALF (adaptive loop filter) APS (adaptationparameter set) includes a first syntax element indicating a presence ofchroma filtering information.

In yet another example aspect, a video encoder apparatus is disclosed.The video encoder comprises a processor configured to implementabove-described methods.

In yet another example aspect, a video decoder apparatus is disclosed.The video decoder comprises a processor configured to implementabove-described methods.

In yet another example aspect, a computer readable medium having codestored thereon is disclose. The code embodies one of the methodsdescribed herein in the form of processor-executable code.

These, and other, features are described throughout the presentdisclosure.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram of an example video processing system.

FIG. 2 is a block diagram of a video processing apparatus.

FIG. 3 is a flowchart for an example method of video processing.

FIG. 4 is a block diagram that illustrates a video coding system inaccordance with some embodiments of the present disclosure.

FIG. 5 is a block diagram that illustrates an encoder in accordance withsome embodiments of the present disclosure.

FIG. 6 is a block diagram that illustrates a decoder in accordance withsome embodiments of the present disclosure.

FIGS. 7A to 7G show flowcharts for example methods of video processingbased on some implementations of the disclosed technology.

DETAILED DESCRIPTION

Section headings are used in the present disclosure for ease ofunderstanding and do not limit the applicability of techniques andembodiments disclosed in each section only to that section. Furthermore,H.266 terminology is used in some description only for ease ofunderstanding and not for limiting scope of the disclosed techniques. Assuch, the techniques described herein are applicable to other videocodec protocols and designs also.

1. Introduction

This document is related to video coding technologies. Specifically, itis about the syntax design of adaption parameter set (APS), deblocking,subpicture, and quantization parameter (QP) delta in video coding. Theideas may be applied individually or in various combination, to anyvideo coding standard or non-standard video codec that supportsmulti-layer video coding, e.g., the being-developed Versatile VideoCoding (VVC).

2. Abbreviations

-   -   ALF Adaptive Loop Filter    -   APS Adaptation Parameter Set    -   AU Access Unit    -   AUD Access Unit Delimiter    -   AVC Advanced Video Coding    -   BDOF Bi-directional Optical Flow    -   CB/Cb Blue Difference Chroma    -   CR/Cr Red Difference Chroma    -   CLVS Coded Layer Video Sequence    -   CPB Coded Picture Buffer    -   CRA Clean Random Access    -   CTB Coding Tree Block    -   CTU Coding Tree Unit    -   CU Coding Unit    -   CVS Coded Video Sequence    -   DPB Decoded Picture Buffer    -   DPS Decoding Parameter Set    -   DMVR Decoder-Side Motion Vector Refinement    -   EOB End Of Bitstream    -   EOS End Of Sequence    -   GDR Gradual Decoding Refresh    -   HEVC High Efficiency Video Coding    -   HRD Hypothetical Reference Decoder    -   ID Identifier    -   IDR Instantaneous Decoding Refresh    -   IRAP Intra Random Access Point    -   JEM Joint Exploration Model    -   LMCS Luma Mapping With Chroma Scaling    -   MCTS Motion-Constrained Tile Sets    -   MVP Motion Vector Prediction    -   NAL Network Abstraction Layer    -   NUT NAL Unit Type    -   OLS Output Layer Set    -   PH Picture Header    -   PPS Picture Parameter Set    -   PROF Prediction Refinement with Optical Flow    -   PTL Profile, Tier and Level    -   PU Picture Unit    -   RADL Random Access Decodable Leading (Picture)    -   RASL Random Access Skipped Leading (Picture)    -   RBSP Raw Byte Sequence Payload    -   SAO Sample Adaptive Offset    -   SEI Supplemental Enhancement Information    -   SH Slice Header    -   SPS Sequence Parameter Set    -   SVC Scalable Video Coding    -   MVP Motion Vector Prediction    -   VCL Video Coding Layer    -   VPS Video Parameter Set    -   VTM VVC Test Model    -   VUI Video Usability Information    -   VVC Versatile Video Coding    -   WP Weighted Prediction    -   Y Luminance

3. Initial Discussion

Video coding standards have evolved primarily through the development ofthe well-known International Telecommunication Union—TelecommunicationStandardization Sector (ITU-T) and International Organization forStandardization (ISO)/International Electrotechnical Commission (IEC)standards. The ITU-T produced H.261 and H.263, ISO/IEC produced MovingPicture Experts Group (MPEG)-1 and MPEG-4 Visual, and the twoorganizations jointly produced the H.262/MPEG-2 Video and H.264/MPEG-4Advanced Video Coding (AVC) and H.265/HEVC standards. Since H.262, thevideo coding standards are based on the hybrid video coding structurewherein temporal prediction plus transform coding are utilized. Toexplore the future video coding technologies beyond HEVC, the JointVideo Exploration Team (JVET) was founded by Video Coding Experts Group(VCEG) and MPEG jointly in 2015. Since then, many new methods have beenadopted by JVET and put into the reference software named JointExploration Model (JEM). The JVET meeting is concurrently held onceevery quarter, and the new coding standard is targeting at 50% bitratereduction as compared to HEVC. The new video coding standard wasofficially named as Versatile Video Coding (VVC) in the April 2018 JVETmeeting, and the first version of VVC test model (VTM) was released atthat time. As there are continuous effort contributing to VVCstandardization, new coding techniques are being adopted to the VVCstandard in every JVET meeting. The VVC working draft and test model VTMare then updated after every meeting. The VVC project is now aiming fortechnical completion (FDIS) at the July 2020 meeting.

3.1. PPS Syntax and Semantics

In the latest VVC draft text, the PPS syntax and semantics are asfollows:

Descriptor pic_parameter_set_rbsp( ) {  pps_pic_parameter_set_id ue(v) pps_seq_parameter_set_id u(4)  mixed_nalu_types_in_pic_flag u(1) pic_width_in_luma_samples ue(v)  pic_height_in_luma_samples ue(v) pps_conformance_window_flag u(1)  if( pps_conformance_window_flag ) {  pps_conf_win_left_offset ue(v)   pps_conf_win_right_offset ue(v)  pps_conf_win_top_offset ue(v)   pps_conf_win_bottom_offset ue(v)  } scaling_window_explicit_signalling_flag u(1)  if(scaling_window_explicit_signalling_flag ) {   scaling_win_left_offsetue(v)   scaling_win_right_offset ue(v)   scaling_win_top_offset ue(v)  scaling_win_bottom_offset ue(v)  }  output_flag_present_flag u(1) subpic_id_mapping_in_pps_flag u(1)  if( subpic_id_mapping_in_pps_flag ){   pps_num_subpics_minus1 ue(v)   pps_subpic_id_len_minus1 ue(v)   for(i = 0; i <= pps_num_subpic_minus1; i++ )    pps_subpic_id[ i ] u(v)  } no_pic_partition_flag u(1)  if( !no_pic_partition_flag ) {  pps_log2_ctu_size_minus5 u(2)   num_exp_tile_columns_minus1 ue(v)  num_exp_tile_rows_minus1 ue(v)   for( i = 0; i <=num_exp_tile_columns_minus1; i++ )    tile_column_width_minus1[ i ]ue(v)   for( i = 0; i <= num_exp_tile_rows_minus1; i++ )   tile_row_height_minus1[ i ] ue(v)   if( NumTilesInPic > 1 )   rect_slice_flag u(1)   if( rect_slice_flag )   single_slice_per_subpic_flag u(1)   if( rect_slice_flag &&!single_slice_per_subpic_flag   ) {    num_slices_in_pic_minus1 ue(v)   if( num_slices_in_pic_minus1 > 0 )     tile_idx_delta_present_flagu(1)    for( i = 0; i < num_slices_in_pic_minus1; i++ ) {     if(NumTileColumns > 1 )      slice_width_in_tiles_minus1[ i ] ue(v)     if(NumTileRows > 1 &&       ( tile_idx_delta_present_flag || tileIdx %NumTileColumns = = 0 ) )      slice_height_in_tiles_minus1[ i ] ue(v)    if( slice_width_in_tiles_minus1[ i ] = = 0 &&      slice_height_in_tiles_minus1[ i ] = = 0 &&  RowHeight[SliceTopLeftTileIdx[ i ] / NumTileColumns ]  > 1 ) {     num_exp_slices_in_tile[ i ] ue(v)      for( j = 0; j <num_exp_slices_in_tile[ i ]; j++      )      exp_slice_height_in_ctus_minus1[ j ] ue(v)      i +=NumSlicesInTile[ i ] − 1     }     if( tile_idx_delta_present_flag && i< num_slices_in_pic_minus1 )      tile_idx_delta[ i ] se(v)    }   }  loop_filter_across_tiles_enabled_flag u(1)  loop_filter_across_slices_enabled_flag u(1)  } cabac_init_present_flag u(1)  for( i = 0; i < 2; i++ )  num_ref_idx_default_active_minus1[ i ] ue(v)  rpl1_idx_present_flagu(1)  init_qp_minus26 se(v)  cu_qp_delta_enabled_flag u(1) pps_chroma_tool_offsets_present_flag u(1)  if(pps_chroma_tool_offsets_present_flag ) {   pps_cb_qp_offset se(v)  pps_cr_qp_offset se(v)   pps_joint_cbcr_qp_offset_present_flag u(1)  if( pps_joint_cbcr_qp_offset_present_flag )   pps_joint_cbcr_qp_offset_value se(v)  pps_slice_chroma_qp_offsets_present_flag u(1)  pps_cu_chroma_qp_offset_list_enabled flag u(1)  }  if(pps_cu_chroma_qp_offset_list_enabled_flag ) {  chroma_qp_offset_list_len_minus1 ue(v)   for( i = 0; i <=chroma_qp_offset_list_len_minus1;   i++ ) {    cb_qp_offset_list[ i ]se(v)    cr_qp_offset_list[ i ] se(v)    if(pps_joint_cbcr_qp_offset_present_flag )     joint_cbcr_qp_offset_list[ i] se(v)   }  }  pps_weighted_pred_flag u(1)  pps_weighted_bipred_flagu(1)  deblocking_filter_control_present_flag u(1)  if(deblocking_filter_control_present_flag ) {  deblocking_filter_override_enabled_flag u(1)  pps_deblocking_filter_disabled_flag u(1)   if(!pps_deblocking_filter_disabled_flag ) {    pps_beta_offset_div2 se(v)   pps_tc_offset_div2 se(v)    pps_cb_beta_offset_div2 se(v)   pps_cb_tc_offset_div2 se(v)    pps_cr_beta_offset_div2 se(v)   pps_cr_tc_offset_div2 se(v)   }  }  rpl_info_in_ph_flag u(1)  if(deblocking_filter_override_enabled_flag )   dbf_info_in_ph_flag u(1) sao_info_in_ph_flag u(1)  alf_info_in_ph_flag u(1)  if( (pps_weighted_pred_flag || pps_weighted_bipred_flag ) &&rpl_info_in_ph_flag )   wp_info_in_ph_flag u(1) qp_delta_info_in_ph_flag u(1)  pps_ref_wraparound_enabled_flag u(1) if( pps_ref_wraparound_enabled_flag )   pps_ref_wraparound_offset ue(v) picture_header_extension_present_flag u(1) slice_header_extension_present_flag u(1)  pps_extension_flag u(1)  if(pps_extension_flag )   while( more_rbsp_data( ) )   pps_extension_data_flag u(1)  rbsp_trailing_bits( ) }A PPS RBSP shall be available to the decoding process prior to it beingreferenced, included in at least one AU with TemporalId less than orequal to the TemporalId of the PPS NAL unit or provided through externalmeans.All PPS NAL units with a particular value of pps_pic_parameter_set_idwithin a PU shall have the same content. pps_pic_parameter_set_ididentifies the PPS for reference by other syntax elements. The value ofpps_pic_parameter_set_id shall be in the range of 0 to 63, inclusive.PPS NAL units, regardless of the nuh_layer_id values, share the samevalue space of pps_pic_parameter_set_id. Let ppsLayerId be the value ofthe nuh_layer_id of a particular PPS NAL unit, and vclLayerId be thevalue of the nuh_layer_id of a particular VCL NAL unit. The particularVCL NAL unit shall not refer to the particular PPS NAL unit unlessppsLayerId is less than or equal to vclLayerId and the layer withnuh_layer_id equal to ppsLayerId is included in at least one OLS thatincludes the layer with nuh_layer_id equal to vclLayerId.pps_seq_parameter_set_id specifies the value of sps_seq_parameter_set_idfor the SPS. The value of pps_seq_parameter_set_id shall be in the rangeof 0 to 15, inclusive. The value of pps_seq_parameter_set_id shall bethe same in all PPSs that are referred to by coded pictures in a CLVS.mixed_nalu_types_in_pic_flag equal to 1 specifies that each picturereferring to the PPS has more than one VCL NAL unit, the VCL NAL unitsdo not have the same value of nal_unit_type, and the picture is not anIRAP picture. mixed_nalu_types_in_pic_flag equal to 0 specifies thateach picture referring to the PPS has one or more VCL NAL units and theVCL NAL units of each picture referring to the PPS have the same valueof nal_unit_type.When no_mixed_nalu_types_in_pic_constraint_flag is equal to 1, the valueof mixed_nalu_types_in_pic_flag shall be equal to 0.For each slice with a nal_unit_type value nalUnitTypeA in the range ofIDR_W_RADL to CRA_NUT, inclusive, in a picture picA that also containsone or more slices with another value of nal_unit_type (i.e., the valueof mixed_nalu_types_in_pic_flag for the picture picA is equal to 1), thefollowing applies:

-   -   The slice shall belong to a subpicture subpicA for which the        value of the corresponding subpic_treated_as_pic_flag[i] is        equal to 1.    -   The slice shall not belong to a subpicture of picA containing        VCL NAL units with nal_unit_type not equal to nalUnitTypeA.    -   If nalUnitTypeA is equal to CRA, for all the following PUs        following the current picture in the CLVS in decoding order and        in output order, neither RefPicList[0] nor RefPicList[1] of a        slice in subpicA in those PUs shall include any picture        preceding picA in decoding order in an active entry.    -   Otherwise (i.e., nalUnitTypeA is equal to IDR_W_RADL or        IDR_N_LP), for all the PUs in the CLVS following the current        picture in decoding order, neither RefPicList[0] nor        RefPicList[1] of a slice in subpicA in those PUs shall include        any picture preceding picA in decoding order in an active entry.        -   NOTE 1—mixed_nalu_types_in_pic_flag equal to 1 indicates            that pictures referring to the PPS contain slices with            different NAL unit types, e.g., coded pictures originating            from a subpicture bitstream merging operation for which            encoders have to ensure matching bitstream structure and            further alignment of parameters of the original bitstreams.            One example of such alignments is as follows: When the value            of sps_idr_rpl_flag is equal to 0 and            mixed_nalu_types_in_pic_flag is equal to 1, a picture            referring to the PPS cannot have slices with nal_unit_type            equal to IDR_W_RADL or IDR_N_LP.            pic_width_in_luma_samples specifies the width of each            decoded picture referring to the PPS in units of luma            samples. pic_width_in_luma_samples shall not be equal to 0,            shall be an integer multiple of Max(8, MinCbSizeY), and            shall be less than or equal to            pic_width_max_in_luma_samples.            When res_change_in_clvs_allowed_flag equal to 0, the value            of pic_width_in_luma_samples shall be equal to            pic_width_max_in_luma_samples.            pic_height_in_luma_samples specifies the height of each            decoded picture referring to the PPS in units of luma            samples. pic_height_in_luma_samples shall not be equal to 0            and shall be an integer multiple of Max(8, MinCbSizeY), and            shall be less than or equal to            pic_height_max_in_luma_samples.            When res_change_in_clvs_allowed_flag equal to 0, the value            of pic_height_in_luma_samples shall be equal to            pic_height_max_in_luma_samples.            The variables PicWidthInCtbsY, PicHeightInCtbsY,            PicSizeInCtbsY, PicWidthInMinCbsY, PicHeightInMinCbsY,            PicSizeInMinCbsY, PicSizeInSamplesY, PicWidthInSamplesC and            PicHeightInSamplesC are derived as follows:

PicWidthInCtbsY=Ceil(pic_width_in_luma_samples+CtbSizeY)  (69)

PicHeightInCtbsY=Ceil(pic_height_in_luma_samples+CtbSizeY)  (70)

PicSizeInCtbsY=PicWidthInCtbsY*PicHeightInCtbsY  (71)

PicWidthInMinCbsY=pic_width_in_luma_samples/MinCbSizeY  (72)

PicHeightInMinCbsY=pic_height_in_luma_samples/MinCbSizeY  (73)

PicSizeInMinCbsY=PicWidthInMinCbsY*PicHeightInMinCbsY  (74)

PicSizeInSamplesY=pic_width_in_luma_samples*pic_height_in_luma_samples  (75)

PicWidthInSamplesC=pic_width_in_luma_samples/SubWidthC  (76)

PicHeightInSamplesC=pic_height_in_luma_samples/SubHeightC  (77)

pps_conformance_window_flag equal to 1 indicates that the conformancecropping window offset parameters follow next in the PPS.pps_conformance_window_flag equal to 0 indicates that the conformancecropping window offset parameters are not present in the PPS.pps_conf_win_left_offset, pps_conf_win_right_offset, pps_confwin_top_offset, and pps_conf_win_bottom_offset specify the samples ofthe pictures in the CLVS that are output from the decoding process, interms of a rectangular region specified in picture coordinates foroutput. When pps_conformance_window_flag is equal to 0, the values ofpps_conf_win_left_offset, pps_conf_win_right_offset,pps_conf_win_top_offset, and pps_conf_win_bottom_offset are inferred tobe equal to 0.The conformance cropping window contains the luma samples withhorizontal picture coordinates from SubWidthC*pps_conf_win_left_offsetto pic_width_in_luma_samples−(SubWidthC*pps_conf_win_right_offset+1) andvertical picture coordinates from SubHeightC*pps_conf_win_top_offset topic_height_in_luma_samples−(SubHeightC*pps_conf_win_bottom_offset+1),inclusive.The value ofSubWidthC*(pps_conf_win_left_offset+pps_conf_win_right_offset) shall beless than pic_width_in_luma_samples, and the value ofSubHeightC*(pps_conf_win_top_offset+pps_conf_win_bottom_offset) shall beless than pic_height_in_luma_samples.When ChromaArrayType is not equal to 0, the corresponding specifiedsamples of the two chroma arrays are the samples having picturecoordinates (x/SubWidthC, y/SubHeightC), where (x, y) are the picturecoordinates of the specified luma samples.

-   -   NOTE 2—The conformance cropping window offset parameters are        only applied at the output. All internal decoding processes are        applied to the uncropped picture size.        Let ppsA and ppsB be any two PPSs referring to the same SPS. It        is a requirement of bitstream conformance that, when ppsA and        ppsB have the same the values of pic_width_in_luma_samples and        pic_height_in_luma_samples, respectively, ppsA and ppsB shall        have the same values of pps_conf_win_left_offset,        pps_conf_win_right_offset, pps_conf_win_top_offset, and        pps_conf_win_bottom_offset, respectively.        When pic_width_in_luma_samples is equal to        pic_width_max_in_luma_samples and pic_height_in_luma_samples is        equal to pic_height_max_in_luma_samples, it is a requirement of        bitstream conformance that pps_conf_win_left_offset,        pps_conf_win_right_offset, pps_conf_win_top_offset, and        pps_conf_win_bottom_offset, are equal to        sps_conf_win_left_offset, sps_conf_win_right_offset,        sps_conf_win_top_offset, and sps_conf_win_bottom_offset,        respectively.        scaling_window_explicit_signalling_flag equal to 1 specifies        that the scaling window offset parameters are present in the        PPS. scaling_window_explicit_signalling_flag equal to 0        specifies that the scaling window offset parameters are not        present in the PPS. When res_change_in_clvs_allowed_flag is        equal to 0, the value of scaling_window_explicit_signalling_flag        shall be equal to 0.        scaling_win_left_offset, scaling_win_right_offset,        scaling_win_top_offset, and scaling_win_bottom_offset specify        the offsets that are applied to the picture size for scaling        ratio calculation. When not present, the values of        scaling_win_left_offset, scaling_win_right_offset,        scaling_win_top_offset, and scaling_win_bottom_offset are        inferred to be equal to pps_conf_win_left_offset,        pps_conf_win_right_offset, pps_conf_win_top_offset, and        pps_conf_win_bottom_offset, respectively.        The value of        SubWidthC*(scaling_win_left_offset+scaling_win_right_offset)        shall be less than pic_width_in_luma_samples, and the value of        SubHeightC*(scaling_win_top_offset+scaling_win_bottom_offset)        shall be less than pic_height_in_luma_samples.        The variables PicOutputWidthL and PicOutputHeightL are derived        as follows:

PicOutputWidthL=pic_width_in_luma_samples−SubWidthC*(scaling_win_right_offset+scaling_win_left_offset)  (78)

PicOutputHeightL=pic_height_in_luma_samples−SubWidthC*(scaling_win_bottom_offset+scaling_win_top_offset)  (79)

Let refPicOutputWidthL and refPicOutputHeightL be the PicOutputWidthLand PicOutputHeightL, respectively, of a reference picture of a currentpicture referring to this PPS. Is a requirement of bitstream conformancethat all of the following conditions are satisfied:

-   -   PicOutputWidthL*2 shall be greater than or equal to        refPicWidthInLumaSamples.    -   PicOutputHeightL*2 shall be greater than or equal to        refPicHeightInLumaSamples.    -   PicOutputWidthL shall be less than or equal to        refPicWidthInLumaSamples*8.    -   PicOutputHeightL shall be less than or equal to        refPicHeightInLumaSamples*8.    -   PicOutputWidthL*pic_width_max_in_luma_samples shall be greater        than or equal to        refPicOutputWidthL*(pic_width_in_luma_samples−Max(8,        MinCbSizeY)).    -   PicOutputHeightL*pic_height_max_in_luma_samples shall be greater        than or equal to        refPicOutputHeightL*(pic_height_in_luma_samples−Max(8,        MinCbSizeY)).        output_flag_present_flag equal to 1 indicates that the        pic_output_flag syntax element is present in slice headers        referring to the PPS. output_flag_present_flag equal to 0        indicates that the pic_output_flag syntax element is not present        in slice headers referring to the PPS.        subpic_id_mapping_in_pps_flag equal to 1 specifies that the        subpicture ID mapping is signalled in the PPS.        subpic_id_mapping_in_pps_flag equal to 0 specifies that the        subpicture ID mapping is not signalled in the PPS. If        subpic_id_mapping_explicitly_signalled_flag is 0 or        subpic_id_mapping_in_sps_flag is equal to 1, the value of        subpic_id_mapping_in_pps_flag shall be equal to 0. Otherwise        (subpic_id_mapping_explicitly_signalled_flag is equal to 1 and        subpic_id_mapping_in_sps_flag is equal to 0), the value of        subpic_id_mapping_in_pps_flag shall be equal to 1.        pps_num_subpics_minus1 shall be equal to sps_num_subpics_minus1.        pps_subpic_id_len_minus1 shall be equal to        sps_subpic_id_len_minus1.        pps_subpic_id[i] specifies the subpicture ID of the i-th        subpicture. The length of the pps_subpic_id[i] syntax element is        pps_subpic_id_len_minus1+1 bits.        The variable SubpicIdVal[i], for each value of i in the range of        0 to sps_num_subpics_minus1, inclusive, is derived as follows:

for( i = 0; i <= sps_num_subpics_minus1; i++ )  if(subpic_id_mapping_explicitly_signalled_flag )   SubpicIdVal[ i ] =subpic_id_mapping_in_pps_flag ?   pps_subpic_id[ i ] : sps_subpic_id[ i]  (80)  else   SubpicIdVal[ i ] = iIt is a requirement of bitstream conformance that both of the followingconstraints apply:

-   -   For any two different values of i and j in the range of 0 to        sps_num_subpics_minus1, inclusive, SubpicIdVal[i] shall not be        equal to SubpicIdVal[j].    -   When the current picture is not the first picture of the CLVS,        for each value of i in the range of 0 to sps_num_subpics_minus1,        inclusive, if the value of SubpicIdVal[i] is not equal to the        value of SubpicIdVal[i] of the previous picture in decoding        order in the same layer, the nal_unit_type for all coded slice        NAL units of the subpicture in the current picture with        subpicture index i shall be equal to a particular value in the        range of IDR_W_RADL to CRA_NUT, inclusive.        no_pic_partition_flag equal to 1 specifies that no picture        partitioning is applied to each picture referring to the PPS.        no_pic_partition_flag equal to 0 specifies each picture        referring to the PPS may be partitioned into more than one tile        or slice.        It is a requirement of bitstream conformance that the value of        no_pic_partition_flag shall be the same for all PPSs that are        referred to by coded pictures within a CLVS.        It is a requirement of bitstream conformance that the value of        no_pic_partition_flag shall not be equal to 1 when the value of        sps_num_subpics_minus1+1 is greater than 1.        pps_log 2_ctu_size_minus5 plus 5 specifies the luma coding tree        block size of each CTU. pps_log 2_ctu_size_minus5 shall be equal        to sps_log 2_ctu_size_minus5.        num_exp_tile_columns_minus1 plus 1 specifies the number of        explicitly provided tile column widths. The value of        num_exp_tile_columns_minus1 shall be in the range of 0 to        PicWidthInCtbsY−1, inclusive. When no_pic_partition_flag is        equal to 1, the value of num_exp_tile_columns_minus1 is inferred        to be equal to 0.        num_exp_tile_rows_minus1 plus 1 specifies the number of        explicitly provided tile row heights. The value of        num_exp_tile_rows_minus1 shall be in the range of 0 to        PicHeightInCtbsY−1, inclusive. When no_pic_partition_flag is        equal to 1, the value of num_tile_rows_minus1 is inferred to be        equal to 0.        tile_column_width_minus1[i] plus 1 specifies the width of the        i-th tile column in units of CTBs for i in the range of 0 to        num_exp_tile_columns_minus1−1, inclusive.        tile_column_width_minus1[num_exp_tile_columns_minus1] is used to        derive the width of the tile columns with index greater than or        equal to num_exp_tile_columns_minus1 as specified in clause        6.5.1. The value of tile_column_width_minus1[i] shall be in the        range of 0 to PicWidthInCtbsY−1, inclusive. When not present,        the value of tile_column_width_minus1[0] is inferred to be equal        to PicWidthInCtbsY−1.        tile_row_height_minus1[i] plus 1 specifies the height of the        i-th tile row in units of CTBs for i in the range of 0 to        num_exp_tile_rows_minus1−1, inclusive.        tile_row_height_minus1[num_exp_tile_rows_minus1] is used to        derive the height of the tile rows with index greater than or        equal to num_exp_tile_rows_minus1 as specified in clause 6.5.1.        The value of tile_row_height_minus1[i] shall be in the range of        0 to PicHeightInCtbsY−1, inclusive. When not present, the value        of tile_row_height_minus1[0] is inferred to be equal to        PicHeightInCtbsY−1.        rect_slice_flag equal to 0 specifies that tiles within each        slice are in raster scan order and the slice information is not        signalled in PPS. rect_slice_flag equal to 1 specifies that        tiles within each slice cover a rectangular region of the        picture and the slice information is signalled in the PPS. When        not present, rect_slice_flag is inferred to be equal to 1. When        subpic_info_present_flag is equal to 1, the value of        rect_slice_flag shall be equal to 1.        single_slice_per_subpic_flag equal to 1 specifies that each        subpicture consists of one and only one rectangular slice.        single_slice_per_subpic_flag equal to 0 specifies that each        subpicture may consist of one or more rectangular slices. When        single_slice_per_subpic_flag is equal to 1,        num_slices_in_pic_minus1 is inferred to be equal to        sps_num_subpics_minus1. When not present, the value of        single_slice_per_subpic_flag is inferred to be equal to 0.        num_slices_in_pic_minus1 plus 1 specifies the number of        rectangular slices in each picture referring to the PPS. The        value of num_slices_in_pic_minus1 shall be in the range of 0 to        MaxSlicesPerPicture−1, inclusive, where MaxSlicesPerPicture is        specified in Annex A. When no_pic_partition_flag is equal to 1,        the value of num_slices_in_pic_minus1 is inferred to be equal to        0.        tile_idx_delta_present_flag equal to 0 specifies that        tile_idx_delta values are not present in the PPS and all        rectangular slices in pictures referring to the PPS are        specified in raster order according to the process defined in        clause 6.5.1. tile_idx_delta_present_flag equal to 1 specifies        that tile_idx_delta values may be present in the PPS and all        rectangular slices in pictures referring to the PPS are        specified in the order indicated by the values of        tile_idx_delta.        When not present, the value of tile_idx_delta_present_flag is        inferred to be equal to 0. slice_width_in_tiles_minus1[i] plus 1        specifies the width of the i-th rectangular slice in units of        tile columns. The value of slice_width_in_tiles_minus1[i] shall        be in the range of 0 to NumTileColumns−1, inclusive.        When slice_width_in_files_minus1[i] is not present, the        following applies:    -   If NumTileColumns is equal to 1, the value of        slice_width_in_tiles_minus1[i] is inferred to be equal to 0.    -   Otherwise, the value of slice_width_in_files_minus1[i] is        inferred as specified in clause 6.5.1.        slice_height_in_tiles_minus1[i] plus 1 specifies the height of        the i-th rectangular slice in units of tile rows. The value of        slice_height_in_tiles_minus1[i] shall be in the range of 0 to        NumTileRows−1, inclusive.        When slice_height_in_tiles_minus1[i] is not present, the        following applies:    -   If NumTileRows is equal to 1, or tile_idx_delta_present_flag is        equal to 0 and tileIdx % NumTileColumns is greater than 0), the        value of slice_height_in_tiles_minus1[i] is inferred to be equal        to 0.    -   Otherwise (NumTileRows is not equal to 1, and        tile_idx_delta_present_flag is equal to 1 or tileIdx %        NumTileColumns is equal to 0), when tile_idx_delta_present_flag        is equal to 1 or tileIdx % NumTileColumns is equal to 0, the        value of slice_height_in_tiles_minus1[i] is inferred to be equal        to slice_height_in_tiles_minus1[i−1].        num_exp_slices_in_tile[i] specifies the number of explicitly        provided slice heights in the current tile that contains more        than one rectangular slices. The value of        num_exp_slices_in_tile[i] shall be in the range of 0 to        RowHeight[tileY]−1, inclusive, where tileY is the tile row index        containing the i-th slice. When not present, the value of        num_exp_slices_in_tile[i] is inferred to be equal to 0. When        num_exp_slices_in_tile[i] is equal to 0, the value of the        variable NumSlicesInTile[i] is derived to be equal to 1.        exp_slice_height_in_ctus_minus1[j] plus 1 specifies the height        of the j-th rectangular slice in the current tile in units of        CTU rows. The value of exp_slice_height_in_ctus_minus1[j] shall        be in the range of 0 to RowHeight[tileY]−1, inclusive, where        tileY is the tile row index of the current tile.        When num_exp_slices_in_tile[i] is greater than 0, the variable        NumSlicesInTile[i] and SliceHeightInCtusMinus1[i+k] for k in the        range of 0 to NumSlicesInTile[i]−1 are derived as follows:

remainingHeightInCtbsY = RowHeight[ SliceTopLeftTileIdx[ i ] /NumTileColumns ] numExpSliceInTile = num_exp_slices_in_tile[ i ] for( j= 0; j < numExpSliceInTile − 1; j++ ) {  SliceHeightInCtusMinus1[ i++ ]=  exp_slice_height_in_ctu_minus1[ j ]  remainingHeightInCtbsY −=SliceHeightInCtusMinus1[ j ] } uniformSliceHeightMinus1 =SliceHeightInCtusMinus1[ i − 1 ] (81) while( remainingHeightInCtbsY >=(uniformSliceHeightMinus1 + 1) ) {  SliceHeightInCtusMinus1[ i++ ] =uniformSliceHeightMinus1  remainingHeightInCtbsY −=(uniformSliceHeightMinus1 + 1)  j++ } if( remainingHeightInCtbsY > 0 ) { SliceHeightInCtusMinus1[ i++ ] = remainingHeightInCtbsY  j++ }NumSlicesInTile[ i ] = jtile_idx_delta[i] specifies the difference between the tile index of thefirst tile in the i-th rectangular slice and the tile index of the firsttile in the (i+1)-th rectangular slice. The value of tile_idx_delta[i]shall be in the range of −NumTilesInPic+1 to NumTilesInPic−1, inclusive.When not present, the value of tile_idx_delta[i] is inferred to be equalto 0. When present, the value of tile_idx_delta[i] shall not be equal to0.loop_filter_across_tiles_enabled_flag equal to 1 specifies that in-loopfiltering operations may be performed across tile boundaries in picturesreferring to the PPS. loop_filter_across_tiles_enabled_flag equal to 0specifies that in-loop filtering operations are not performed acrosstile boundaries in pictures referring to the PPS. The in-loop filteringoperations include the deblocking filter, sample adaptive offset filter,and adaptive loop filter operations. When not present, the value ofloop_filter_across_tiles_enabled_flag is inferred to be equal to 1.loop_filter_across_slices_enabled_flag equal to 1 specifies that in-loopfiltering operations may be performed across slice boundaries inpictures referring to the PPS. loop_filter_across_slice_enabled_flagequal to 0 specifies that in-loop filtering operations are not performedacross slice boundaries in pictures referring to the PPS. The in-loopfiltering operations include the deblocking filter, sample adaptiveoffset filter, and adaptive loop filter operations. When not present,the value of loop_filter_across_slices_enabled_flag is inferred to beequal to 0.cabac_init_present_flag equal to 1 specifies that cabac_init_flag ispresent in slice headers referring to the PPS. cabac_init_present_flagequal to 0 specifies that cabac_init_flag is not present in sliceheaders referring to the PPS.num_ref_idx_default_active_minus1[i] plus 1, when i is equal to 0,specifies the inferred value of the variable NumRefIdxActive[0] for P orB slices with num_ref_idx_active_override_flag equal to 0, and, when iis equal to 1, specifies the inferred value of NumRefIdxActive[1] for Bslices with num_ref_idx_active_override_flag equal to 0. The value ofnum_ref_idx_default_active_minus1[i] shall be in the range of 0 to 14,inclusive.rpl1_idx_present_flag equal to 0 specifies that ref_pic_list_sps_flag[1]and ref_pic_list_idx[1] are not present in the PH syntax structures orthe slice headers for pictures referring to the PPS.rpl1_idx_present_flag equal to 1 specifies that ref_pic_list_sps_flag[1]and ref_pic_list_idx[1] may be present in the PH syntax structures orthe slice headers for pictures referring to the PPS.init_qp_minus26 plus 26 specifies the initial value of SliceQp_(Y) foreach slice referring to the PPS. The initial value of SliceQp_(Y) ismodified at the picture level when a non-zero value of ph_qp_delta isdecoded or at the slice level when a non-zero value of slice_qp_delta isdecoded. The value of init_qp_minus26 shall be in the range of−(26+QpBdOffset) to +37, inclusive.cu_qp_delta_enabled_flag equal to 1 specifies that theph_cu_qp_delta_subdiv_intra_slice and ph_cu_qp_delta_subdiv_inter_slicesyntax elements are present in PHs referring to the PPS andcu_qp_delta_abs may be present in the transform unit syntax.cu_qp_delta_enabled_flag equal to 0 specifies that theph_cu_qp_delta_subdiv_intra_slice and ph_cu_qp_delta_subdiv_inter_slicesyntax elements are not present in PHs referring to the PPS andcu_qp_delta_abs is not present in the transform unit syntax.pps_chroma_tool_offsets_present_flag equal to 1 specifies that chromatool offsets related syntax elements are present in the PPS RBSP syntaxstructure. pps_chroma_tool_offsets_present_flag equal to 0 specifiesthat chroma tool offsets related syntax elements are not present in inthe PPS RBSP syntax structure. When ChromaArrayType is equal to 0, thevalue of pps_chroma_tool_offsets_present_flag shall be equal to 0.pps_cb_qp_offset and pps_cr_qp_offset specify the offsets to the lumaquantization parameter Qp′_(Y) used for deriving Qp′_(Cb) and Qp′_(Cr),respectively. The values of pps_cb_qp_offset and pps_cr_qp_offset shallbe in the range of −12 to +12, inclusive. When ChromaArrayType is equalto 0, pps_cb_qp_offset and pps_cr_qp_offset are not used in the decodingprocess and decoders shall ignore their value. When not present, thevalues of pps_cb_qp_offset and pps_cr_qp_offset are inferred to be equalto 0.pps_joint_cbcr_qp_offset_present_flag equal to 1 specifies thatpps_joint_cbcr_qp_offset_value and joint_cbcr_qp_offset_list[i] arepresent in the PPS RBSP syntax structure.pps_joint_cbcr_qp_offset_present_flag equal to 0 specifies thatpps_joint_cbcr_qp_offset_value and joint_cbcr_qp_offset_list[i] are notpresent in the PPS RBSP syntax structure. When ChromaArrayType is equalto 0 or sps_joint_cbcr_enabled_flag is equal to 0, the value ofpps_joint_cbcr_qp_offset_present_flag shall be equal to 0. When notpresent, the value of pps_joint_cbcr_qp_offset_present_flag is inferredto be equal to 0.pps_joint_cbcr_qp_offset_value specifies the offset to the lumaquantization parameter Qp′_(Y) used for deriving Qp′_(CbCr). The valueof pps_joint_cbcr_qp_offset_value shall be in the range of −12 to +12,inclusive. When ChromaArrayType is equal to 0 orsps_joint_cbcr_enabled_flag is equal to 0,pps_joint_cbcr_qp_offset_value is not used in the decoding process anddecoders shall ignore its value. Whenpps_joint_cbcr_qp_offset_present_flag is equal to 0,pps_joint_cbcr_qp_offset_value is not present and is inferred to beequal to 0.pps_slice_chroma_qp_offsets_present_flag equal to 1 specifies that theslice_cb_qp_offset and slice_cr_qp_offset syntax elements are present inthe associated slice headers. pps_slice_chroma_qp_offsets_present_flagequal to 0 specifies that the slice_cb_qp_offset and slice_cr_qp_offsetsyntax elements are not present in the associated slice headers. Whennot present, the value of pps_slice_chroma_qp_offsets_present_flag isinferred to be equal to 0.pps_cu_chroma_qp_offset_list_enabled_flag equal to 1 specifies that theph_cu_chroma_qp_offset_subdiv_intra_slice andph_cu_chroma_qp_offset_subdiv_inter_slice syntax elements are present inPHs referring to the PPS and cu_chroma_qp_offset_flag may be present inthe transform unit syntax and the palette coding syntax.pps_cu_chroma_qp_offset_list_enabled_flag equal to 0 specifies that theph_cu_chroma_qp_offset_subdiv_intra_slice andph_cu_chroma_qp_offset_subdiv_inter_slice syntax elements are notpresent in PHs referring to the PPS and the cu_chroma_qp_offset_flag isnot present in the transform unit syntax and the palette coding syntax.When not present, the value of pps_cu_chroma_qp_offset_list_enabled_flagis inferred to be equal to 0.chroma_qp_offset_list_len_minus1 plus 1 specifies the number ofcb_qp_offset_list[i], cr_qp_offset_list[i], andjoint_cbcr_qp_offset_list[i], syntax elements that are present in thePPS RBSP syntax structure. The value of chroma_qp_offset_list_len_minus1shall be in the range of 0 to 5, inclusive. cb_qp_offset_list[i],cr_qp_offset_list[i], and joint_cbcr_qp_offset_list[i], specify offsetsused in the derivation of Qp′_(Cb), Qp′_(Cr), and Qp′_(CbCr),respectively. The values of cb_qp_offset_list[i], cr_qp_offset_list[i],and joint_cbcr_qp_offset_list[i] shall be in the range of −12 to +12,inclusive. When pps_joint_cbcr_qp_offset_present_flag is equal to 0,joint_cbcr_qp_offset_list[i] is not present and it is inferred to beequal to 0.pps_weighted_pred_flag equal to 0 specifies that weighted prediction isnot applied to P slices referring to the PPS. pps_weighted_pred_flagequal to 1 specifies that weighted prediction is applied to P slicesreferring to the PPS. When sps_weighted_pred_flag is equal to 0, thevalue of pps_weighted_pred_flag shall be equal to 0.pps_weighted_bipred_flag equal to 0 specifies that explicit weightedprediction is not applied to B slices referring to the PPS.pps_weighted_bipred_flag equal to 1 specifies that explicit weightedprediction is applied to B slices referring to the PPS. Whensps_weighted_bipred_flag is equal to 0, the value ofpps_weighted_bipred_flag shall be equal to 0.deblocking_filter_control_present_flag equal to 1 specifies the presenceof deblocking filter control syntax elements in the PPS.deblocking_filter_control_present_flag equal to 0 specifies the absenceof deblocking filter control syntax elements in the PPS.deblocking_filter_override_enabled_flag equal to 1 specifies thepresence of ph_deblocking_filter_override_flag in the PHs referring tothe PPS or slice_deblocking_filter_override_flag in the slice headersreferring to the PPS. deblocking_filter_override_enabled_flag equal to 0specifies the absence of ph_deblocking_filter_override_flag in PHsreferring to the PPS or slice_deblocking_filter_override_flag in sliceheaders referring to the PPS. When not present, the value ofdeblocking_filter_override_enabled_flag is inferred to be equal to 0.pps_deblocking_filter_disabled_flag equal to 1 specifies that theoperation of deblocking filter is not applied for slices referring tothe PPS in which slice_deblocking_filter_disabled_flag is not present.pps_deblocking_filter_disabled_flag equal to 0 specifies that theoperation of the deblocking filter is applied for slices referring tothe PPS in which slice_deblocking_filter_disabled_flag is not present.When not present, the value of pps_deblocking_filter_disabled_flag isinferred to be equal to 0.pps_beta_offset_div2 and pps_tc_offset_div2 specify the defaultdeblocking parameter offsets for β and tC (divided by 2) that areapplied to the luma component for slices referring to the PPS, unlessthe default deblocking parameter offsets are overridden by thedeblocking parameter offsets present in the picture headers or the sliceheaders of the slices referring to the PPS. The values ofpps_beta_offset_div2 and pps_tc_offset_div2 shall both be in the rangeof −12 to 12, inclusive. When not present, the values ofpps_beta_offset_div2 and pps_tc_offset_div2 are both inferred to beequal to 0.pps_cb_beta_offset_div2 and pps_cb_tc_offset_div2 specify the defaultdeblocking parameter offsets for β and tC (divided by 2) that areapplied to the Cb component for slices referring to the PPS, unless thedefault deblocking parameter offsets are overridden by the deblockingparameter offsets present in the picture headers or the slice headers ofthe slices referring to the PPS. The values of pps_cb_beta_offset_div2and pps_cb_tc_offset_div2 shall both be in the range of −12 to 12,inclusive. When not present, the values of pps_cb_beta_offset_div2 andpps_cb_tc_offset_div2 are both inferred to be equal to 0.pps_cr_beta_offset_div2 and pps_cr_tc_offset_div2 specify the defaultdeblocking parameter offsets for β and tC (divided by 2) that areapplied to the Cr component for slices referring to the PPS, unless thedefault deblocking parameter offsets are overridden by the deblockingparameter offsets present in the picture headers or the slice headers ofthe slices referring to the PPS. The values of pps_cr_beta_offset_div2and pps_cr_tc_offset_div2 shall both be in the range of −12 to 12,inclusive. When not present, the values of pps_cr_beta_offset_div2 andpps_cr_tc_offset_div2 are both inferred to be equal to 0.rpl_info_in_ph_flag equal to 1 specifies that reference picture listinformation is present in the PH syntax structure and not present inslice headers referring to the PPS that do not contain a PH syntaxstructure. rpl_info_in_ph_flag equal to 0 specifies that referencepicture list information is not present in the PH syntax structure andmay be present in slice headers referring to the PPS that do not containa PH syntax structure.dbf_info_in_ph_flag equal to 1 specifies that deblocking filterinformation is present in the PH syntax structure and not present inslice headers referring to the PPS that do not contain a PH syntaxstructure. dbf_info_in_ph_flag equal to 0 specifies that deblockingfilter information is not present in the PH syntax structure and may bepresent in slice headers referring to the PPS that do not contain a PHsyntax structure. When not present, the value of dbf_info_in_ph_flag isinferred to be equal to 0.sao_info_in_ph_flag equal to 1 specifies that SAO filter information ispresent in the PH syntax structure and not present in slice headersreferring to the PPS that do not contain a PH syntax structure.sao_info_in_ph_flag equal to 0 specifies that SAO filter information isnot present in the PH syntax structure and may be present in sliceheaders referring to the PPS that do not contain a PH syntax structure.alf_info_in_ph_flag equal to 1 specifies that ALF information is presentin the PH syntax structure and not present in slice headers referring tothe PPS that do not contain a PH syntax structure. alf_info_in_ph_flagequal to 0 specifies that ALF information is not present in the PHsyntax structure and may be present in slice headers referring to thePPS that do not contain a PH syntax structure.wp_info_in_ph_flag equal to 1 specifies that weighted predictioninformation may be present in the PH syntax structure and not present inslice headers referring to the PPS that do not contain a PH syntaxstructure. wp_info_in_ph_flag equal to 0 specifies that weightedprediction information is not present in the PH syntax structure and maybe present in slice headers referring to the PPS that do not contain aPH syntax structure. When not present, the value of wp_info_in_ph_flagis inferred to be equal to 0.qp_delta_info_in_ph_flag equal to 1 specifies that QP delta informationis present in the PH syntax structure and not present in slice headersreferring to the PPS that do not contain a PH syntax structure.qp_delta_info_in_ph_flag equal to 0 specifies that QP delta informationis not present in the PH syntax structure and may be present in sliceheaders referring to the PPS that do not contain a PH syntax structure.pps_ref_wraparound_enabled_flag equal to 1 specifies that horizontalwrap-around motion compensation is applied in inter prediction.pps_ref_wraparound_enabled_flag equal to 0 specifies that horizontalwrap-around motion compensation is not applied. When the value ofCtbSizeY/MinCbSizeY+1 is greater thanpic_width_in_luma_samples/MinCbSizeY−1, the value ofpps_ref_wraparound_enabled_flag shall be equal to 0. Whensps_ref_wraparound_enabled_flag is equal to 0, the value ofpps_ref_wraparound_enabled_flag shall be equal to 0.pps_ref_wraparound_offset plus (CtbSizeY/MinCbSizeY)+2 specifies theoffset used for computing the horizontal wrap-around position in unitsof MinCbSizeY luma samples. The value of pps_ref_wraparound_offset shallbe in the range of 0 to(pic_width_in_luma_samples/MinCbSizeY)−(CtbSizeY/MinCbSizeY)−2,inclusive. The variable PpsRefWraparoundOffset is set equal topps_ref_wraparound_offset+(CtbSizeY/MinCbSizeY)+2.picture_header_extension_present_flag equal to 0 specifies that no PHextension syntax elements are present in PHs referring to the PPS.picture_header_extension_present_flag equal to 1 specifies that PHextension syntax elements are present in PHs referring to the PPS.picture_header_extension_present_flag shall be equal to 0 in bitstreamsconforming to this version of this Specification.slice_header_extension_present_flag equal to 0 specifies that no sliceheader extension syntax elements are present in the slice headers forcoded pictures referring to the PPS. slice_header_extension_present_flagequal to 1 specifies that slice header extension syntax elements arepresent in the slice headers for coded pictures referring to the PPS.slice_header_extension_present_flag shall be equal to 0 in bitstreamsconforming to this version of this Specification.pps_extension_flag equal to 0 specifies that no pps_extension_data_flagsyntax elements are present in the PPS RBSP syntax structure.pps_extension_flag equal to 1 specifies that there arepps_extension_data_flag syntax elements present in the PPS RBSP syntaxstructure.pps_extension_data_flag may have any value. Its presence and value donot affect decoder conformance to profiles specified in this version ofthis Specification. Decoders conforming to this version of thisSpecification shall ignore all pps_extension_data_flag syntax elements.

3.2. APS Syntax and Semantics

In the latest VVC draft text, the APS syntax and semantics are asfollows:

Descriptor adaptation_parameter_set_rbsp( ) { adaptation_parameter_set_id u(5)  aps_params_type u(3)  if(aps_params_type = = ALF_APS )   alf_data( )  else if( aps_params_type == LMCS_APS )   lmcs_data( )  else if( aps_params_type = = SCALING_APS )  scaling_list_data( )  aps_extension_flag u(1)  if( aps_extension_flag)   while( more_rbsp_data( ) )    aps_extension_data_flag u(1) rbsp_trailing_bits( ) }

The APS RBSP contains a ALF syntax structure, i.e., alf_data( ).

Descriptor alf_data( ) {  alf_luma_filter_signal_flag u(1) alf_chroma_filter_signal_flag u(1)  alf_cc_cb_filter_signal_flag u(1) alf_cc_cr_filter_signal_flag u(1)  if( alf_luma_filter_signal_flag ) {  alf_luma_clip_flag u(1)   alf_luma_num_filters_signalled_minus1 ue(v)  if( alf_luma_num_filters_signalled_minus1 > 0 )    for( filtIdx = 0;filtIdx < NumAlfFilters; filtIdx++ )     alf_luma_coeff_delta_idx[filtIdx ] u(v)   for( sfIdx = 0; sfIdx <=  alf_luma_num_filters_signalled_minus1; sfIdx++ )    for( j = 0; j <12; j++ ) {     alf_luma_coeff_abs[ sfIdx ][ j ] ue(v)     if(alf_luma_coeff_abs[ sfIdx ][ j ] )      alf_luma_coeff_sign[ sfIdx ][ j] u(1)    }   if( alf_luma_clip_flag )    for( sfIdx = 0; sfIdx <=alf_luma_num_filters_signalled_minus1; sfIdx++ )     for( j = 0; j < 12;j++ )      alf_luma_clip_idx[ sfIdx ][ j ] u(2)  }  if(alf_chroma_filter_signal_flag ) {   alf_chroma_clip_flag u(1)  alf_chroma_num_alt_filters_minus1 ue(v)   for( altIdx = 0; altIdx <=  alf_chroma_num_alt_filters_minus1; altIdx++ ) {    for( j = 0; j < 6;j++ ) {     alf_chroma_coeff_abs[ altIdx ][ j ] ue(v)     if(alf_chroma_coeff_abs[ altIdx ][ j ] > 0 )      alf_chroma_coeff_sign[altIdx ][ j ] u(1)    }    if( alf_chroma_clip_flag )     for( j = 0; j< 6; j++ )      alf_chroma_clip_idx[ altIdx ][ j ] u(2)   }  }  if(alf_cc_cb_filter_signal_flag ) {   alf_cc_cb_filters_signalled_minus1ue(v)   for( k = 0; k < alf_cc_cb_filters_signalled_minus1 +   1; k++ ){    for( j = 0; j < 7; j++ ) {     alf_cc_cb_mapped_coeff_abs[ k ][ j ]u(3)     if( alf_cc_cb_mapped_coeff_abs[ k ][ j ] )     alf_cc_cb_coeff_sign[ k ][ j ] u(1)    }   }  }  if(alf_cc_cr_filter_signal_flag ) {   alf_cc_cr_filters_signalled_minus1ue(v)   for( k = 0; k < alf_cc_cr_filters_signalled_minus1 +   1; k++ ){    for( j = 0; j < 7; j++ ) {     alf_cc_cr_mapped_coeff_abs[ k ][ j ]u(3)     if( alf_cc_cr_mapped_coeff_abs[ k ][ j ] )     alf_cc_cr_coeff_sign[ k ][ j ] u(1)    }   }  } }

The APS RBSP contains a LMCS syntax structure, i.e., lmcs_data( ).

Descriptor lmcs_data( ) {  lmcs_min_bin_idx ue(v) lmcs_delta_max_bin_idx ue(v)  lmcs_delta_cw_prec_minus1 ue(v)  for( i =lmcs_min_bin_idx; i <= LmcsMaxBinIdx; i++ ) {   lmcs_delta_abs_cw[ i ]u(v)   if( lmcs_delta_abs_cw[ i ] > 0 )    lmcs_delta_sign_cw_flag[ i ]u(1)  }  lmcs_delta_abs_crs u(3)  if( lmcs_delta_abs_crs > 0 )  lmcs_delta_sign_crs_flag u(1) }

The APS RBSP contains a scaling list data syntax structure, i.e.,scaling_list_data( ).

Descriptor scaling_list_data( ) { scaling_matrix_for_lfnst_disabled_flag u(1) scaling_list_chroma_present_flag u(1)  for( id = 0; id < 28; id ++ )  matrixSize = (id < 2 ) ? 2 : ( ( id < 8 ) ? 4 : 8 )   if(scaling_list_chroma_present_flag || ( id % 3 = = 2 )   || ( id = = 27 )) {    scaling_list_copy_mode_flag[ id ] u(1)    if(!scaling_list_copy_mode_flag[ id ] )     scaling_list_pred_mode_flag[ id] u(1)    if( ( scaling_list_copy_mode_flag[ id ] ||scaling_list_pred_mode_flag[ id ] ) &&      id != 0 && id != 2 && id !=8 )     scaling_list_pred_id_delta[ id ] ue(v)    if(!scaling_list_copy_mode_flag[ id ] ) {     nextCoef = 0     if( id > 13) {      scaling_list_dc_coef[ id − 14 ] se(v)      nextCoef +=scaling_list_dc_coef[ id − 14 ]     }     for( i = 0; i < matrixSize *matrixSize; i++ ) {      x = DiagScanOrder[ 3 ][ 3 ][ i ][ 0 ]      y =DiagScanOrder[ 3 ][ 3 ][ i ][ 1 ]      if( !( id > 25 && x >= 4 && y >=4 ) ) {       scaling_list_delta_coef[ id ][ i ] se(v)       nextCoef +=scaling_list_delta_coef[ id ][ i ]      }      ScalingList[ id ][ i ] =nextCoef     }    }   }  } }Each APS RBSP shall be available to the decoding process prior to itbeing referenced, included in at least one AU with TemporalId less thanor equal to the TemporalId of the coded slice NAL unit that refers it orprovided through external means.All APS NAL. units with a particular value ofadaptation_parameter_set_id and a particular value of aps_params_typewithin a PU, regardless of whether they are prefix or suffix APS NALunits, shall have the same content.adaptation_paramter_set_id provides an identifier for the APS forreference by other syntax elements.When aps_params_type is equal to ALF_APS or SCALING_APS, the value ofadaptation_parameter_set_id shall be in the range of 0 to 7, inclusive.When aps_params_type is equal to LMCS_APS, the value ofadaptation_parameter_set_id shall be in the range of 0 to 3, inclusive.Let apsLayerId be the value of the nuh_layer_id of a particular APS NALunit, and vclLayerId be the value of the nuh_layer_id of a particularVCL NAL unit. The particular VCL NAL unit shall not refer to theparticular APS NAL unit unless apsLayerId is less than or equal tovclLayerId and the layer with nuh_layer_id equal to apsLayerId isincluded in at least one OLS that includes the layer with nuh_layer_idequal to vclLayerId.aps_params_type specifies the type of APS parameters carried in the APSas specified in Table 6.

TABLE 6 APS parameters type codes and types of APS parameters Name ofaps_params_type aps_params_type Type of APS parameters 0 ALF_APS ALFparameters 1 LMCS_APS LMCS parameters 2 SCALING_APS Scaling listparameters 3 . . . 7 Reserved ReservedAll APS NAL units with a particular value of aps_params_type, regardlessof the nuh_layer_id values, share the same value space foradaptation_parameter_set_id. APS NAL units with different values ofaps_params_type use separate values spaces foradaptation_parameter_set_id.

-   -   NOTE 1—An APS NAL unit (with a particular value of        adaptation_parameter_set_id and a particular value of        aps_params_type) can be shared across pictures, and different        slices within a picture can refer to different ALF APSs.    -   NOTE 2—A suffix APS NAL unit associated with a particular VCL        NAL unit (this VCL NAL unit precedes the suffix APS NAL unit in        decoding order) is not for use by the particular VCL NAL unit,        but for use by VCL NAL units following the suffix APS NAL unit        in decoding order.        aps_extension_flag equal to 0 specifies that no        aps_extension_data_flag syntax elements are present in the APS        RBSP syntax structure. aps_extension_flag equal to 1 specifies        that there are aps_extension_data_flag syntax elements present        in the APS RBSP syntax structure.        aps_extension_data_flag may have any value. Its presence and        value do not affect decoder conformance to profiles specified in        this version of this Specification. Decoders conforming to this        version of this Specification shall ignore all        aps_extension_data_flag syntax elements.        alf_luma_filter_signal_flag equal to 1 specifies that a luma        filter set is signalled. alf_luma_filter_signal_flag equal to 0        specifies that a luma filter set is not signalled.        alf_chroma_filter_signal_flag equal to 1 specifies that a chroma        filter is signalled. alf_chroma_filter_signal_flag equal to 0        specifies that a chroma filter is not signalled. When        ChromaArrayType is equal to 0,        alf_chroma_filter_signal_flag shall be equal to 0.        At least one of the values of alf_luma_filter_signal_flag,        alf_chroma_filter_signal_flag, alf_cc_cb_filter_signal_flag and        alf_cc_cr_filter_signal_flag shall be equal to 1.        The variable NumAlfFilters specifying the number of different        adaptive loop filters is set equal to 25.        alf_luma_clip_flag equal to 0 specifies that linear adaptive        loop filtering is applied on luma component. alf_luma_clip_flag        equal to 1 specifies that non-linear adaptive loop filtering may        be applied on luma component.        alf_luma_num_filters_signalled_minus1 plus 1 specifies the        number of adaptive loop filter classes for which luma        coefficients can be signalled. The value of        alf_luma_num_filters_signalled_minus1 shall be in the range of 0        to NumAlfFilters−1, inclusive.        alf_luma_coeff_delta_idx[filtIdx] specifies the indices of the        signalled adaptive loop filter luma coefficient deltas for the        filter class indicated by filtIdx ranging from 0 to        NumAlfFilters−1. When alf_luma_coeff_delta_idx[filtIdx] is not        present, it is inferred to be equal to 0. The length of        alf_luma_coeff_delta_idx[filtIdx] is Ceil(Log        2(alf_luma_num_filters_signalled_minus1+1)) bits. The value of        alf_luma_coeff_delta_idx[filtIdx] shall be in the range of 0 to        alf_luma_num_filters_signalled_minus1, inclusive.        alf_luma_coeff_abs[sfIdx][j] specifies the absolute value of the        j-th coefficient of the signalled luma filter indicated by        sfIdx. When alf_luma_coeff_abs[sfIdx][j] is not present, it is        inferred to be equal 0. The value of        alf_luma_coeff_abs[sfIdx][j] shall be in the range of 0 to 128,        inclusive. alf_luma_coeff_sign[sfIdx][j] specifies the sign of        the j-th luma coefficient of the filter indicated by sfIdx as        follows:    -   If alf_luma_coeff_sign[sfIdx][j] is equal to 0, the        corresponding luma filter coefficient has a positive value.    -   Otherwise (alf_luma_coeff_sign[sfIdx][j] is equal to 1), the        corresponding luma filter coefficient has a negative value.        When alf_luma_coeff_sign[sfIdx][j] is not present, it is        inferred to be equal to 0.        The variable filtCoeff[sfIdx][j] with sfIdx=0 . . .        alf_luma_num_filters_signalled_minus1, j=0 . . . 11 is        initialized as follows:

filtCoeff[sfIdx][j]=alf_luma_coeff_abs[sfIdx][j]*(1−2*alf_luma_coeff_sign[sfIdx][j])  (93)

The luma filter coefficients AlfCoeff_(L)[adaptation_parameter_set_id]with elements AlfCoeff_(L)[adaptation_parameter_set_id][filtIdx][j],with filtIdx=0 . . . NumAlfFilters−1 and j=0 . . . 11 are derived asfollows:

AlfCoeff_(L)[adaptation_parameter_set_id][filtIdx][j]=filtCoeff[alf_luma_coeff_delta_idx[filtIdx]][j]  (94)

The fixed filter coefficients AlfFixFiltCoeff[i][j] with i=0 . . . 64,j=0 . . . 11 and the class to filter mapping AlfClassToFiltMap[m][n]with m=0 . . . 15 and n=0 . . . 24 are derived as follows:

AlfFixFiltCoeff = (95)  {   { 0, 0, 2, −3, 1, −4, 1, 7, −1, 1, −1, 5}  { 0, 0, 0, 0, 0, −1, 0, 1, 0, 0, −1, 2}   { 0, 0, 0, 0, 0, 0, 0, 1, 0,0, 0, 0}   { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, −1, 1}   { 2, 2, −7, −3, 0,−5, 13, 22, 12, −3, −3, 17}   {−1, 0, 6, −8, 1, −5, 1, 23, 0, 2, −5, 10}  { 0, 0, −1, −1, 0, −1, 2, 1, 0, 0, −1, 4}   { 0, 0, 3, −11, 1, 0, −1,35, 5, 2, −9, 9}   { 0, 0, 8, −8, −2, −7, 4, 4, 2, 1, −1, 25}   { 0, 0,1, −1, 0, −3, 1, 3, −1, 1, −1, 3}   { 0, 0, 3, −3, 0, −6, 5, −1, 2, 1,−4, 21}   {−7, 1, 5, 4, −3, 5, 11, 13, 12, −8, 11, 12}   {−5, −3, 6, −2,−3, 8, 14, 15, 2, −7, 11, 16}   { 2, −1, −6, −5, −2, −2, 20, 14, −4, 0,−3, 25}   { 3, 1, −8, −4, 0, −8, 22, 5, −3, 2, −10, 29}   { 2, 1, −7,−1, 2, −11, 23, −5, 0, 2, −10, 29}   {−6, −3, 8, 9, −4, 8, 9, 7, 14, −2,8, 9}   { 2, 1, −4, −7, 0, −8, 17, 22, 1, −1, −4, 23}   { 3, 0, −5, −7,0, −7, 15, 18, −5, 0, −5, 27}   { 2, 0, 0, −7, 1, −10, 13, 13, −4, 2,−7, 24}   { 3, 3, −13, 4, −2, −5, 9, 21, 25, −2, −3, 12}   {−5, −2, 7,−3, −7, 9, 8, 9, 16, −2, 15, 12}   { 0, −1, 0, −7, −5, 4, 11, 11, 8, −6,12, 21}   { 3, −2, −3, −8, −4, −1, 16, 15, −2, −3, 3, 26}   { 2, 1, −5,−4, −1, −8, 16, 4, −2, 1, −7, 33}   { 2, 1, −4, −2, 1, −10, 17, −2, 0,2, −11, 33}   { 1, −2, 7, −15, −16, 10, 8, 8, 20, 11, 14, 11}   { 2, 2,3, −13, −13, 4, 8, 12, 2, −3, 16, 24}   { 1, 4, 0, −7, −8, −4, 9, 9, −2,−2, 8, 29}   { 1, 1, 2, −4, −1, −6, 6, 3, −1, −1, −3, 30}   {−7, 3, 2,10, −2, 3, 7, 11, 19, −7, 8, 10}   { 0, −2, −5, −3, −2, 4, 20, 15, −1,−3, −1, 22}   { 3, −1, −8, −4, −1, −4, 22, 8, −4, 2, −8, 28}   { 0, 3,−14, 3, 0, 1, 19, 17, 8, −3, −7, 20}   { 0, 2, −1, −8, 3, −6, 5, 21, 1,1, −9, 13}   {−4, −2, 8, 20, −2, 2, 3, 5, 21, 4, 6, 1}   { 2, −2, −3,−9, −4, 2, 14, 16, 3, −6, 8, 24}   { 2, 1, 5, −16, −7, 2, 3, 11, 15, −3,11, 22}   { 1, 2, 3, −11, −2, −5, 4, 8, 9, −3, −2, 26}   { 0, −1, 10,−9, −1, −8, 2, 3, 4, 0, 0, 29}   { 1, 2, 0, −5, 1, −9, 9, 3, 0, 1, −7,20}   {−2, 8, −6, −4, 3, −9, −8, 45, 14, 2, −13, 7}   { 1, −1, 16, −19,−8, −4, −3, 2, 19, 0, 4, 30}   { 1, 1, −3, 0, 2, −11, 15, −5, 1, 2, −9,24}   { 0, 1, −2, 0, 1, −4, 4, 0, 0, 1, −4, 7}   { 0, 1, 2, −5, 1, −6,4, 10, −2, 1, −4, 10}   { 3, 0, −3, −6, −2, −6, 14, 8, −1, −1, −3, 31}  { 0, 1, 0, −2, 1, −6, 5, 1, 0, 1, −5, 13}   { 3, 1, 9, −19, −21, 9, 7,6, 13, 5, 15, 21}   { 2, 4, 3, −12, −13, 1, 7, 8, 3, 0, 12, 26}   { 3,1, −8, −2, 0, −6, 18, 2, −2, 3, −10, 23}   { 1, 1, −4, −1, 1, −5, 8, 1,−1, 2, −5, 10}   { 0, 1, −1, 0, 0, −2, 2, 0, 0, 1, −2, 3}   { 1, 1, −2,−7, 1, −7, 14, 18, 0, 0, −7, 21}   { 0, 1, 0, −2, 0, −7, 8, 1, −2, 0,−3, 24}   { 0, 1, 1, −2, 2, −10, 10, 0, −2, 1, −7, 23}   { 0, 2, 2, −11,2, −4, −3, 39, 7, 1, −10, 9}   { 1, 0, 13, −16, −5, −6, −1, 8, 6, 0, 6,29}   { 1, 3, 1, −6, −4, −7, 9, 6, −3, −2, 3, 33}   { 4, 0, −17, −1, −1,5, 26, 8, −2, 3, −15, 30}   { 0, 1, −2, 0, 2, −8, 12, −6, 1, 1, −6, 16}  { 0, 0, 0, −1, 1, −4, 4, 0, 0, 0, −3, 11}   { 0, 1, 2, −8, 2, −6, 5,15, 0, 2, −7, 9}   { 1, −1, 12, −15, −7, −2, 3, 6, 6, −1, 7, 30}  },AlfClassToFiltMap = (96)  {   { 8, 2, 2, 2, 3, 4, 53, 9, 9, 52, 4, 4, 5,9, 2,  8, 10, 9, 1, 3, 39, 39, 10, 9, 52 }   { 11, 12, 13, 14, 15, 30,11, 17, 18, 19, 16, 20, 20, 4, 53,  21, 22, 23, 14, 25, 26, 26, 27, 28,10 }   { 16, 12, 31, 32, 14, 16, 30, 33, 53, 34, 35, 16, 20, 4, 7,  16,21, 36, 18, 19, 21, 26, 37, 38, 39 }   { 35, 11, 13, 14, 43, 35, 16, 4,34, 62, 35, 35, 30, 56, 7,  35, 21, 38, 24, 40, 16, 21, 48, 57, 39 }   {11, 31, 32, 43, 44, 16, 4, 17, 34, 45, 30, 20, 20, 7, 5,  21, 22, 46,40, 47, 26, 48, 63, 58, 10 }   { 12, 13, 50, 51, 52, 11, 17, 53, 45, 9,30, 4, 53, 19, 0,  22, 23, 25, 43, 44, 37, 27, 28, 10, 55 }   { 30, 33,62, 51, 44, 20, 41, 56, 34, 45, 20, 41, 41, 56, 5,  30, 56, 38, 40, 47,11, 37, 42, 57, 8 }   { 35, 11, 23, 32, 14, 35, 20, 4, 17, 18, 21, 20,20, 20, 4,  16, 21, 36, 46, 25, 41, 26, 48, 49, 58 }   { 12, 31, 59, 59,3, 33, 33, 59, 59, 52, 4, 33, 17, 59, 55,  22, 36, 59, 59, 60, 22, 36,59, 25, 55 }   { 31, 25, 15, 60, 60, 22, 17, 19, 55, 55, 20, 20, 53, 19,55,  22, 46, 25, 43, 60, 37, 28, 10, 55, 52 }   { 12, 31, 32, 50, 51,11, 33, 53, 19, 45, 16, 4, 4, 53, 5,  22, 36, 18, 25, 43, 26, 27, 27,28, 10 }   { 5, 2, 44, 52, 3, 4, 53, 45, 9, 3, 4, 56, 5, 0, 2,  5, 10,47, 52, 3, 63, 39, 10, 9, 52 }   { 12, 34, 44, 44, 3, 56, 56, 62, 45, 9,56, 56, 7, 5, 0,  22, 38, 40, 47, 52, 48, 57, 39, 10, 9 }   { 35, 11,23, 14, 51, 35, 20, 41, 56, 62, 16, 20, 41, 56, 7,  16, 21, 38, 24, 40,26, 26, 42, 57, 39 }   { 33, 34, 51, 51, 52, 41, 41, 34, 62, 0, 41, 41,56, 7, 5,  56, 38, 38, 40, 44, 37, 42, 57, 39, 10 }   { 16, 31, 32, 15,60, 30, 4, 17, 19, 25, 22, 20, 4, 53, 19,  21, 22, 46, 25, 55, 26, 48,63, 58, 55 }  },It is a requirement of bitstream conformance that the values ofAlfCoeff_(L)[adaptation_parameter_set_id][filtIdx][j] with filtIdx=0 . .. NumAlfFilters−1, j=0 . . . 11 shall be in the range of −2⁷ to 2⁷−1,inclusive.alf_luma_clip_idx[sfIdx][j] specifies the clipping index of the clippingvalue to use before multiplying by the j-th coefficient of the signalledluma filter indicated by sfIdx. It is a requirement of bitstreamconformance that the values of alf_luma_clip_idx[sfIdx][j] with sfIdx=0. . . alf_luma_num_filters_signalled_minus1 and j=0 . . . 11 shall be inthe range of 0 to 3, inclusive.The luma filter clipping values AlfClip_(L)[adaptation_parameter_set_id]with elements AlfClip_(L)[adaptation_parameter_set_id][filtIdx][j], withfiltIdx=0 . . . NumAlfFilters−1 and j=0 . . . 11 are derived asspecified in Table 8 depending on BitDepth and clipIdx set equal toalf_luma_clip_idx[alf_luma_coeff_delta_idx[filtIdx]][j].alf_chroma_clip_flag equal to 0 specifies that linear adaptive loopfiltering is applied on chroma components;alf_chroma_clip_flag equal to 1 specifies that non-linear adaptive loopfiltering is applied on chroma components. When not present,alf_chroma_clip_flag is inferred to be equal to 0.alf_chroma_num_alt_filters_minus1 plus 1 specifies the number ofalternative filters for chroma components. The value ofalf_chroma_num_alt_filters_minus1 shall be in the range of 0 to 7,inclusive.alf_chroma_coeff_abs[altIdx][j] specifies the absolute value of the j-thchroma filter coefficient for the alternative chroma filter with indexaltIdx. When alf_chroma_coeff_abs[altIdx][j] is not present, it isinferred to be equal 0. The value of alf_chroma_coeff_abs[sfIdx][j]shall be in the range of 0 to 128, inclusive.alf_chroma_coeff_sign[altIdx][j] specifies the sign of the j-th chromafilter coefficient for the alternative chroma filter with index altIdxas follows:

-   -   If alf_chroma_coeff_sign[altIdx][j] is equal to 0, the        corresponding chroma filter coefficient has a positive value.    -   Otherwise (alf_chroma_coeff_sign[altIdx][j] is equal to 1), the        corresponding chroma filter coefficient has a negative value.        When alf_chroma_coeff_sign[altIdx][j] is not present, it is        inferred to be equal to 0.        The chroma filter coefficients        AlfCoeff_(C)[adaptation_parameter_set_id][altIdx] with elements        AlfCoeff_(C)[adaptation_parameter_set_id][altIdx][j], with        altIdx=0 . . . alf_chroma_num_alt_filters_minus1, j=0 . . . 5        are derived as follows:

AlfCoeff_(C)[adaptation_parameter_set_id][altIdx][j]=alf_chroma_coeff_abs[altIdx][j]*(1−2*alf_chroma_coeff_sign[altIdx][j])  (97)

It is a requirement of bitstream conformance that the values ofAlfCoeff_(C)[adaptation_parameter_set_id][altIdx][j] with altIdx=0 . . .alf_chroma_num_alt_filters_minus1, j=0 . . . 5 shall be in the range of−2⁷ to 2⁷−1, inclusive.alf_cc_cb_filter_signal_flag equal to 1 specifies that cross-componentfilters for the Cb colour component are signalled.alf_cc_cb_filter_signal_flag equal to 0 specifies that cross-componentfilters for Cb colour component are not signalled. When ChromaArrayTypeis equal to 0, alf_cc_cb_filter_signal_flag shall be equal to 0.alf_cc_cb_filters_signalled_minus1 plus 1 specifies the number ofcross-component filters for the Cb colour component signalled in thecurrent ALF APS. The value of alf_cc_cb_filters_signalled_minus1 shallbe in the range of 0 to 3, inclusive.alf_cc_cb_mapped_coeff_abs[k][j] specifies the absolute value of thej-th mapped coefficient of the signalled k-th cross-component filter forthe Cb colour component. When alf_cc_cb_mapped_coeff_abs[k][j] is notpresent, it is inferred to be equal to 0.alf_cc_cb_coeff_sign[k][j] specifies the sign of the j-th coefficient ofthe signalled k-th cross-component filter for the Cb colour component asfollows:

-   -   If alf_cc_cb_coeff_sign[k][j] is equal to 0, the corresponding        cross-component filter coefficient has a positive value.    -   Otherwise (alf_cc_cb_sign[k][j] is equal to 1), the        corresponding cross-component filter coefficient has a negative        value.        When alf_cc_cb_coeff_sign[k][j] is not present, it is inferred        to be equal to 0.        The signalled k-th cross-component filter coefficients for the        Cb colour component        CcAlfApsCoeff_(Cb)[adaptation_parameter_set_id][k][j], with j=0        . . . 6 are derived as follows:    -   If alf_cc_cb_mapped_coeff_abs[k][j] is equal to 0,        CcAlfApsCoeff_(Cb)[adaptation_parameter_set_id][k][j] is set        equal to 0.    -   Otherwise, CcAlfApsCoeff_(Cb)[adaptation_parameter_set_id][k][j]        is set equal to        (1−2*alf_cc_cb_coeff_sign[k][j])*2^(air_cc_cb_mapped_coef_abs[k][j]-1).        alf_cc_cr_filter_signal_flag equal to 1 specifies that        cross-component filters for the Cr colour component are        signalled. alf_cc_cr_filter_signal_flag equal to 0 specifies        that cross-component filters for the Cr colour component are not        signalled. When ChromaArrayType is equal to 0,        alf_cc_cr_filter_signal_flag shall be equal to 0.        alf_cc_cr_filters_signalled_minus1 plus 1 specifies the number        of cross-component filters for the Cr colour component signalled        in the current ALF APS. The value of        alf_cc_cr_filters_signalled_minus1 shall be in the range of 0 to        3, inclusive.        alf_cc_cr_mapped_coeff_abs[k][j] specifies the absolute value of        the j-th mapped coefficient of the signalled k-th        cross-component filter for the Cr colour component. When        alf_cc_cr_mapped_coeff_abs[k][j] is not present, it is inferred        to be equal to 0.        alf_cc_cr_coeff_sign[k][j] specifies the sign of the j-th        coefficient of the signalled k-th cross-component filter for the        Cr colour component as follows:    -   If alf_cc_cr_coeff_sign[k][j] is equal to 0, the corresponding        cross-component filter coefficient has a positive value.    -   Otherwise (alf_cc_cr_sign[k][j] is equal to 1), the        corresponding cross-component filter coefficient has a negative        value.        When alf_cc_cr_coeff_sign[k][j] is not present, it is inferred        to be equal to 0.        The signalled k-th cross-component filter coefficients for the        Cr colour component        CcAlfApsCoeff_(Cr)[adaptation_parameter_set_id][k][j], with j=0        . . . 6 are derived as follows:    -   If alf_cc_cr_mapped_coeff_abs[k][j] is equal to 0,        CcAlfApsCoeff_(Cr)[adaptation_parameter_set_id][k][j] is set        equal to 0.    -   Otherwise, CcAlfApsCoeff_(Cr)[adaptation_parameter_set_id][k][j]        is set equal to        (1−2*alf_cc_cr_coeff_sign[k][j])*2^(alf_cc_cr_mapped_coeff_abs[k][j]-1).        alf_chroma_clip_idx[altIdx][j] specifies the clipping index of        the clipping value to use before multiplying by the j-th        coefficient of the alternative chroma filter with index altIdx.        It is a requirement of bitstream conformance that the values of        alf_chroma_clip_idx[altIdx][j] with altIdx=0 . . .        alf_chroma_num_alt_filters_minus1, j=0 . . . 5 shall be in the        range of 0 to 3, inclusive.        The chroma filter clipping values        AlfClip_(C)[adaptation_parameter_set_id][altIdx] with elements        AlfClip_(C)[adaptation_parameter_set_id][altIdx][j], with        altIdx=0 . . . alf_chroma_num_alt_filters_minus1, j=0 . . . 5        are derived as specified in Table 8 depending on BitDepth and        clipIdx set equal to alf_chroma_clip_idx[altIdx][j].

TABLE 8 Specification AlfClip depending on BitDepth and clipIdx clipIdxBitDepth 0 1 2 3 8 2⁸  2⁵ 2³ 2¹ 9 2⁹  2⁶ 2⁴ 2² 10 2¹⁰ 2⁷ 2⁵ 2³ 11 2¹¹ 2⁸2⁶ 2⁴ 12 2¹² 2⁹ 2⁷ 2⁵ 13 2¹³  2¹⁰ 2⁸ 2⁶ 14 2¹⁴  2¹¹ 2⁹ 2⁷ 15 2¹⁵  2¹² 2¹⁰ 2⁸ 16 2¹⁶  2¹³  2¹¹ 2⁹lmcs_min_bin_idx specifies the minimum bin index used in the lumamapping with chroma scaling construction process. The value oflmcs_min_bin_idx shall be in the range of 0 to 15, inclusive.lmcs_delta_max_bin_idx specifies the delta value between 15 and themaximum bin index LmcsMaxBinIdx used in the luma mapping with chromascaling construction process. The value of lmcs_delta_max_bin_idx shallbe in the range of 0 to 15, inclusive. The value of LmcsMaxBinIdx is setequal to 15−lmcs_delta_max_bin_idx. The value of LmcsMaxBinIdx shall begreater than or equal to lmcs_min_bin_idx.lmcs_delta_cw_prec_minus1 plus 1 specifies the number of bits used forthe representation of the syntax lmcs_delta_abs_cw[i]. The value oflmcs_delta_cw_prec_minus1 shall be in the range of 0 to BitDepth−2,inclusive.lmcs_delta_abs_cw[i] specifies the absolute delta codeword value for theith bin.lmcs_delta_sign_cw_flag[i] specifies the sign of the variablelmcsDeltaCW[i] as follows:

-   -   If lmcs_delta_sign_cw_flag[i] is equal to 0, lmcsDeltaCW[i] is a        positive value.    -   Otherwise (lmcs_delta_sign_cw_flag[i] is not equal to 0),        lmcsDeltaCW[i] is a negative value.        When lmcs_delta_sign_cw_flag[i] is not present, it is inferred        to be equal to 0.        The variable OrgCW is derived as follows:

OrgCW=(1<<BitDepth)/16  (98)

The variable lmcsDeltaCW[i], with i=lmcs_min_bin_idx . . .LmcsMaxBinIdx, is derived as follows:

lmcsDeltaCW[i]=(1−2*lmcs_delta_sign_cw_flag[i])*lmcs_delta_abs_cw[i]  (99)

The variable lmcsCW[i] is derived as follows:

-   -   For i=0 . . . lmcs_min_bin_idx−1, lmcsCW[i] is set equal 0.    -   For i=lmcs_min_bin_idx . . . LmcsMaxBinIdx, the following        applies:

lmcsCW[i]=OrgCW+lmcsDeltaCW[i]  (100)

The value of lmcsCW[i] shall be in the range of (OrgCW>>3) to(OrgCW<<3−1), inclusive.

-   -   For i=LmcsMaxBinIdx+1 . . . 15, lmcsCW[i] is set equal 0.        It is a requirement of bitstream conformance that the following        condition is true:

Σ_(i=0) ¹⁵lmcsCW[i]<=(1<<BitDepth)−1  (101)

The variable InputPivot[i], with i=0 . . . 16, is derived as follows:

InputPivot[i]=i*OrgCW  (102)

The variable LmcsPivot[i] with i=0 . . . 16, the variables ScaleCoeff[i]and InvScaleCoeff[i] with i=0 . . . 15, are derived as follows:

LmcsPivot[ 0 ] = 0; for( i = 0; i <= 15; i++ ) {  LmcsPivot[ i + 1 ] =LmcsPivot[ i ] + lmcsCW[ i ]  ScaleCoeff[ i ] = ( lmcsCW[ i ] * (1 << 11) + ( 1 << ( Log2(  OrgCW ) − 1 ) ) ) >> ( Log2( OrgCW ) )  if( lmcsCW[i ] = = 0 ) (103)   InvScaleCoeff[ i ] = 0  else   InvScaleCoeff[ i ] =OrgCW * ( 1 << 11 ) / lmcsCW[ i ] }It is a requirement of bitstream conformance that, fori=lmcs_min_bin_idx . . . LmcsMaxBinIdx, when the value of LmcsPivot[i]is not a multiple of 1<<(BitDepth−5), the value of(LmcsPivot[i]>>(BitDepth−5)) shall not be equal to the value of(LmcsPivot[i+1]>>(BitDepth−5)).lmcs_delta_abs_crs specifies the absolute codeword value of the variablelmcsDeltaCrs. The value of lmcs_delta_abs_crs shall be in the range of 0and 7, inclusive. When not present, lmcs_delta_abs_crs is inferred to beequal to 0.lmcs_delta_sign_crs_flag specifies the sign of the variablelmcsDeltaCrs. When not present, lmcs_delta_sign_crs_flag is inferred tobe equal to 0.The variable lmcsDeltaCrs is derived as follows:

lmcsDeltaCrs=(1−2*lmcs_delta_sign_crs_flag)*lmcs_delta_abs_crs  (104)

It is a requirement of bitstream conformance that, when lmcsCW[i] is notequal to 0, (lmcsCW[i]+lmcsDeltaCrs) shall be in the range of (OrgCW>>3)to ((OrgCW<<3)−1), inclusive.The variable ChromaScaleCoeff[i], with i=0 . . . 15, is derived asfollows:

if( lmcsCW[ i ] = = 0 )  ChromaScaleCoeff[ i ] = ( 1 << 11 ) else ChromaScaleCoeff[ i ] = OrgCW * ( 1 << 11 ) / ( lmcsCW[ i ] + lmcsDeltaCrs )scaling_matrix_for_lfnst_disabled_flag equal to 1 specifies that scalingmatrices are not applied to blocks coded with LFNST.scaling_matrix_for_lfnst_disabled_flag equal to 0 specifies that thescaling matrices may apply to the blocks coded with LFNST.scaling_list_chroma_present_flag equal to 1 specifies that chromascaling lists are present in scaling_list_data( ).scaling_list_chroma_present_flag equal to 0 specifies that chromascaling lists are not present in scaling_list_data( ). It is arequirement of bitstream conformance thatscaling_list_chroma_present_flag shall be equal to 0 whenChromaArrayType is equal to 0, and shall be equal to 1 whenChromaArrayType is not equal to 0.scaling_list_copy_mode_flag[id] equal to 1 specifies that the values ofthe scaling list are the same as the values of a reference scaling list.The reference scaling list is specified byscaling_list_pred_id_delta[id]. scaling_list_copy_mode_flag[id] equal to0 specifies that scaling_list_pred_mode_flag is present.scaling_list_pred_mode_flag[id] equal to 1 specifies that the values ofthe scaling list can be predicted from a reference scaling list. Thereference scaling list is specified by scaling_list_pred_id_delta[id].scaling_list_pred_mode_flag[id] equal to 0 specifies that the values ofthe scaling list are explicitly signalled.When not present, the value of scaling_list_pred_mode_flag[id] isinferred to be equal to 0.scaling_list_pred_id_delta[id] specifies the reference scaling list usedto derive the predicted scaling matrix ScalingMatrixPred[id]. When notpresent, the value of scaling_list_pred_id_delta[id] is inferred to beequal to 0. The value of scaling_list_pred_id_delta[id] shall be in therange of 0 to maxIdDelta with maxIdDelta derived depending on id asfollows:

maxIdDelta=(id<2)?id:((id<8)?(id−2):(id−8))  (106)

The variables refId and matrixSize are derived as follows:

refId=id−scaling_list_pred_id_delta[id]  (107)

matrixSize=(id<2)?2:((id<8)?4:8)  (108)

The (matrixSize)×(matrixSize) array ScalingMatrixPred[x][y] with x=0 . .. matrixSize−1, y=0 . . . matrixSize−1 and the variableScalingMatrixDCPred are derived as follows:

-   -   When both scaling_list_copy_mode_flag[id] and        scaling_list_pred_mode_flag[id] are equal to 0, all elements of        ScalingMatrixPred are set equal to 8, and the value of        ScalingMatrixDCPred is set equal to 8.    -   Otherwise, when scaling_list_pred_id_delta[id] is equal to 0,        all elements of ScalingMatrixPred are set equal to 16, and        ScalingMatrixDCPred is set equal to 16.    -   Otherwise (either scaling_list_copy_mode_flag[id] or        scaling_list_pred_mode_flag[id] is equal to 1 and        scaling_list_pred_id_delta[id] is greater than 0),        ScalingMatrixPred is set equal to ScalingMatrixRec[refId], and        the following applies for ScalingMatrixDCPred:        -   If refId is greater than 13, ScalingMatrixDCPred is set            equal to ScalingMatrixDCRec[refId−14].        -   Otherwise (refId is less than or equal to 13),            ScalingMatrixDCPred is set equal to ScalingMatrixPred[0][0].            scaling_list_dc_coef[id−14] is used to derive the value of            the variable ScalingMatrixDC[id−14] when id is greater than            13 as follows:

ScalingMatrixDCRec[id−14]=(ScalingMatrixDCPred+scaling_list_dc_coef[id−14])& 255  (109)

When not present, the value of scaling_list_dc_coef[id−14] is inferredto be equal to 0. The value of scaling_list_dc_coef[id−14] shall be inthe range of −128 to 127, inclusive. The value ofScalingMatrixDCRec[id−14] shall be greater than 0.scaling_list_delta_coef[id][i] specifies the difference between thecurrent matrix coefficient ScalingList[id][i] and the previous matrixcoefficient ScalingList[id][i−1], when scaling_list_copy_mode_flag[id]is equal to 0.The value of scaling_list_delta_coef[id][i] shall be in the range of−128 to 127, inclusive. When scaling_list_copy_mode_flag[id] is equal to1, all elements of ScalingList[id] are set equal to 0.The (matrixSize)×(matrixSize) array ScalingMatrixRec[id] is derived asfollows:

ScalingMatrixRec[id][x][y]=(ScalingMatrixPred[x][y]+ScalingList[id][k])& 255  (110)

-   -   with k=0 . . . (matrixSize*matrixSize−1),        -   x=DiagScanOrder[Log 2(matrixSize)][Log 2(matrixSize)][k][0],            and        -   y=DiagScanOrder[Log 2(matrixSize)][Log 2(matrixSize)][k][1]            The value of ScalingMatrixRec[id][x][y] shall be greater            than 0.

3.3. PH Syntax and Semantics

In the latest VVC draft text, the PH syntax and semantics are asfollows:

Descriptor picture_header_rbsp( ) {  picture_header_structure( ) rbsp_trailing_bits( ) }

The PH RBSP contains a PH syntax structure, i.e.,picture_header_structure( ).

Descriptor picture_header_structure( ) {  gdr_or_irap_pic_flag u(1)  if(gdr_or_irap_pic flag )   gdr_pic_flag u(1)  ph_inter_slice_allowed_flagu(1)  if( ph_inter_slice_allowed_flag )   ph_intra_slice_allowed_flagu(1)  non_reference_picture_flag u(1)  ph_pic_parameter_set_id ue(v) ph_pic_order_cnt_lsb u(v)  if( gdr_or_irap_pic_flag )  no_output_of_prior_pics_flag u(1)  if( gdr_pic_flag )  recovery_poc_cnt ue(v)  for( i = 0; i < NumExtraPhBits; i++ )  ph_extra_bit[ i ] u(1)  if( sps_poc_msb_flag ) {  ph_poc_msb_present_flag u(1)   if( ph_poc_msb_present_flag )   poc_msb_val u(v)  }  if( sps_alf_enabled_flag && alf_info_in_ph_flag) {   ph_alf_enabled_flag u(1)   if( ph_alf_enabled_flag ) {   ph_num_alf_aps_ids_luma u(3)    for( i = 0; i <ph_num_alf_aps_ids_luma; i++ )     ph_alf_aps_id_luma[ i ] u(3)    if(ChromaArrayType != 0 )     ph_alf_chroma_idc u(2)    if(ph_alf_chroma_idc > 0 )     ph_alf_aps_id_chroma u(3)    if(sps_calf_enabled_flag ) {     ph_cc_alf_cb_enabled_flag u(1)     if(ph_cc_alf_cb_enabled_flag )      ph_cc_alf_cb_aps_id u(3)    ph_cc_alf_cr_enabled_flag u(1)     if( ph_cc_alf_cr_enabled_flag )     ph_cc_alf_cr_aps_id u(3)    }   }  }  if( sps_lmcs_enabled_flag ) {  ph_lmcs_enabled_flag u(1)   if( ph_lmcs_enabled_flag ) {   ph_lmcs_aps_id u(2)    if( ChromaArrayType != 0 )    ph_chroma_residual_scale_flag u(1)   }  }  if(sps_scaling_list_enabled_flag ) {   ph_scaling_list_present_flag u(1)  if( ph_scaling_list_present_flag )    ph_scaling_list_aps_id u(3)  } if( sps_virtual_boundaries_enabled_flag &&!sps_virtual_boundaries_present_flag ) {  ph_virtual_boundaries_present_flag u(1)   if(ph_virtual_boundaries_present_flag ) {    ph_num_ver_virtual_boundariesu(2)    for( i = 0; i < ph_num_ver_virtual_boundaries; i++ )    ph_virtual_boundaries_pos_x[ i ] u(13)   ph_num_hor_virtual_boundaries u(2)    for( i = 0; i <ph_num_hor_virtual_boundaries; i++ )     ph_virtual_boundaries_pos_y[ i] u(13)   }  }  if( output_flag_present_flag)   pic_output_flag u(1) if( rpl_info_in_ph_flag)   ref_pic_lists( )  if(partition_constraints_override_enabled_flag )  partition_constraints_override_flag u(1)  if(ph_intra_slice_allowed_flag ) {   if(partition_constraints_override_flag ) {   ph_log2_diff_min_qt_min_cb_intra_slice_luma ue(v)   ph_max_mtt_hierarchy_depth_intra_slice_luma ue(v)    if(ph_max_mtt_hierarchy_depth_intra_slice_luma != 0 ) {    ph_log2_diff_max_bt_min_qt_intra_slice_luma ue(v)    ph_log2_diff_max_tt_min_qt_intra_slice_luma ue(v)    }    if(qtbtt_dual_tree_intra_flag ) {    ph_log2_diff_min_qt_min_cb_intra_slice_chroma ue(v)    ph_max_mtt_hierarchy_depth_intra_slice_chroma ue(v)     if(ph_max_mtt_hierarchy_depth_intra_slice_chroma != 0 ){ ph_log2_diff_max_bt_min_qt_intra_slice_chroma ue(v) ph_log2_diff_max_tt_min_qt_intra_slice_chroma ue(v)     }    }   }  if( cu_qp_delta_enabled_flag )    ph_cu_qp_delta_subdiv_intra_sliceue(v)   if( pps_cu_chroma_qp_offset_list_enabled_flag )   ph_cu_chroma_qp_offset_subdiv_intra_slice ue(v)  }  if(ph_inter_slice_allowed_flag ) {   if(partition_constraints_override_flag ) {   ph_log2_diff_min_qt_min_cb_inter_slice ue(v)   ph_max_mtt_hierarchy_depth_inter_slice ue(v)    if(ph_max_mtt_hierarchy_depth_inter_slice != 0 ) {    ph_log2_diff_max_bt_min_qt_inter_slice ue(v)    ph_log2_diff_max_tt_min_qt_inter_slice ue(v)    }   }   if(cu_qp_delta_enabled_flag )    ph_cu_qp_delta_subdiv_inter_slice ue(v)  if( pps_cu_chroma_qp_offset_list_enabled_flag )   ph_cu_chroma_qp_offset_subdiv_inter_slice ue(v)   if(sps_temporal_mvp_enabled_flag ) {    ph_temporal_mvp_enabled_flag u(1)   if( ph_temporal_mvp_enabled_flag && rpl_info_in_ph_flag ) {    ph_collocated_from_10_flag u(1)     if( ( ph_collocated_from_10_flag&&       num_ref_entries[ 0 ][ RplsIdx[ 0 ] ] > 1 ) | |       (!ph_collocated_from_10_flag &&       num_ref_entries[ 1 ][ RplsIdx[ 1 ]] > 1 ) )      ph_collocated_ref_idx ue(v)    }   }   mvd_l1_ zero_flagu(1)   if( sps_fpel_mmvd_enabled_flag )    ph_fpel_mmvd_enabled_flagu(1)   if( sps_bdof_pic_present flag )    ph_disable_bdof_flag u(1)  if( sps_dmvr_pic_present_flag )    ph_disable_dmvr_flag u(1)   if(sps_prof_pic_present_flag )    ph_disable_prof_flag u(1)   if( (weighted_pred_flag | | pps_weighted_bipred_flag ) && wp_info_in_ph_flag)    pred_weight_table( )  }  if( qp_delta_info_in_ph_flag )  ph_qp_delta se(v)  if( sps_joint_cbcr_enabled_flag )  ph_joint_cbcr_sign_flag u(1)  if( sps_sao_enabled_flag &&sao_info_in_ph flag ) {   ph_sao_luma_enabled_flag u(1)   if(ChromaArrayType != 0 )    ph_sao_chroma_enabled_flag u(1)  }  if(sps_dep_quant_enabled_flag )   ph_dep_quant_enabled_flag u(1)  if(sps_sign_data_hiding_enabled_flag && !ph_dep_quant_enabled flag )  pic_sign_data_hiding_enabled_flag u(1)  if(deblocking_filter_override_enabled_flag && dbf_info_in_ph_flag ) {  ph_deblocking_filter_override_flag u(1)   if(ph_deblocking_filter_override_flag ) {   ph_deblocking_filter_disabled_flag u(1)    if(!ph_deblocking_filter_disabled_flag ) {     ph_beta_offset_div2 se(v)    ph_tc_offset_div2 se(v)     ph_cb_beta_offset_div2 se(v)    ph_cb_tc_offset_div2 se(v)     ph_cr_beta_offset_div2 se(v)    ph_cr_tc_offset_div2 se(v)    }   }  }  if(picture_header_extension_present_flag ) {   ph_extension_length ue(v)  for( i = 0; i < ph extension length; i++)    ph_extension_data_byte[ i] u(8)  } }The PH syntax structure contains information that is common for allslices of the coded picture associated with the PH syntax structure.gdr_or_irap_pic_flag equal to 1 specifies that the current picture is aGDR or IRAP picture. gdr_or_irap_pic_flag equal to 0 specifies that thecurrent picture may or may not be a GDR or IRAP picture.gdr_pic_flag equal to 1 specifies the picture associated with the PH isa GDR picture. gdr_pic_flag equal to 0 specifies that the pictureassociated with the PH is not a GDR picture. When not present, the valueof gdr_pic_flag is inferred to be equal to 0. When gdr_enabled_flag isequal to 0, the value of gdr_pic_flag shall be equal to 0.ph_inter_slice_allowed_flag equal to 0 specifies that all coded slicesof the picture have slice_type equal to 2. ph_inter_slice_allowed_flagequal to 1 specifies that there may or may not be one or more codedslices in the picture that have slice_type equal to 0 or 1.ph_intra_slice_allowed_flag equal to 0 specifies that all coded slicesof the picture have slice_type equal to 0 or 1.ph_intra_slice_allowed_flag equal to 1 specifies that there may or maynot be one or more coded slices in the picture that have slice_typeequal to 2. When not present, the value of ph_intra_slice_allowed_flagis inferred to be equal to 1.

-   -   NOTE 1—For bitstreams that are supposed to work subpicture based        bitstream merging without the need of changing PH NAL units, the        encoder is expected to set the values of both        ph_inter_slice_allowed_flag and ph_intra_slice_allowed_flag        equal to 1.        non_reference_picture_flag equal to 1 specifies the picture        associated with the PH is never used as a reference picture.        non_reference_picture_flag equal to 0 specifies the picture        associated with the PH may or may not be used as a reference        picture.        ph_pic_parameter_set_id specifies the value of        pps_pic_parameter_set_id for the PPS in use. The value of        ph_pic_parameter_set_id shall be in the range of 0 to 63,        inclusive.        It is a requirement of bitstream conformance that the value of        TemporalId of the PH shall be greater than or equal to the value        of TemporalId of the PPS that has pps_pic_parameter_set_id equal        to ph_pic_parameter_set_id.        ph_pic_order_cnt_lsb specifies the picture order count modulo        MaxPicOrderCntLsb for the current picture. The length of the        ph_pic_order_cnt_lsb syntax element is log        2_max_pic_order_cnt_lsb_minus4+4 bits. The value of the        ph_pic_order_cnt_lsb shall be in the range of 0 to        MaxPicOrderCntLsb−1, inclusive.        no_output_of_prior_pics_flag affects the output of        previously-decoded pictures in the DPB after the decoding of a        CLVSS picture that is not the first picture in the bitstream as        specified in Annex C.        recovery_poc_cnt specifies the recovery point of decoded        pictures in output order. If the current picture is a GDR        picture that is associated with the PH, and there is a picture        picA that follows the current GDR picture in decoding order in        the CLVS that has PicOrderCntVal equal to the PicOrderCntVal of        the current GDR picture plus the value of recovery_poc_cnt, the        picture picA is referred to as the recovery point picture.        Otherwise, the first picture in output order that has        PicOrderCntVal greater than the PicOrderCntVal of the current        picture plus the value of recovery_poc_cnt is referred to as the        recovery point picture. The recovery point picture shall not        precede the current GDR picture in decoding order. The value of        recovery_poc_cnt shall be in the range of 0 to        MaxPicOrderCntLsb−1, inclusive.        When the current picture is a GDR picture, the variable        RpPicOrderCntVal is derived as follows:

RpPicOrderCntVal=PicOrderCntVal+recovery_poc_cnt  (82)

-   -   NOTE 2—When gdr_enabled_flag is equal to 1 and PicOrderCntVal of        the current picture is greater than or equal to RpPicOrderCntVal        of the associated GDR picture, the current and subsequent        decoded pictures in output order are exact match to the        corresponding pictures produced by starting the decoding process        from the previous IRAP picture, when present, preceding the        associated GDR picture in decoding order.        ph_extra_bit[i] may be equal to 1 or 0. Decoders conforming to        this version of this Specification shall ignore the value of        ph_extra_bit[i]. Its value does not affect decoder conformance        to profiles specified in this version of specification.        ph_poc_msb_present_flag equal to 1 specifies that the syntax        element poc_msb_val is present in the PH.        ph_poc_msb_present_flag equal to 0 specifies that the syntax        element poc_msb_val is not present in the PH. When        vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id]] is        equal to 0 and there is a picture in the current AU in a        reference layer of the current layer, the value of        ph_poc_msb_present_flag shall be equal to 0.        poc_msb_val specifies the POC MSB value of the current picture.        The length of the syntax element poc_msb_val is        poc_msb_len_minus1+1 bits.        ph_alf_enabled_flag equal to 1 specifies that adaptive loop        filter is enabled for all slices associated with the PH and may        be applied to Y, Cb, or Cr colour component in the slices.        ph_alf_enabled_flag equal to 0 specifies that adaptive loop        filter may be disabled for one, or more, or all slices        associated with the PH. When not present, ph_alf_enabled_flag is        inferred to be equal to 0.        ph_num_alf_aps_ids_luma specifies the number of ALF APSs that        the slices associated with the PH refers to.        ph_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id        of the i-th ALF APS that the luma component of the slices        associated with the PH refers to.        The value of alf_luma_filter_signal_flag of the APS NAL unit        having aps_params_type equal to ALF_APS and        adaptation_parameter_set_id equal to ph_alf_aps_id_luma[i] shall        be equal to 1.        The TemporalId of the APS NAL unit having aps_params_type equal        to ALF_APS and adaptation_parameter_set_id equal to        ph_alf_aps_id_luma[i] shall be less than or equal to the        TemporalId of the picture associated with the PH.        ph_alf_chroma_idc equal to 0 specifies that the adaptive loop        filter is not applied to Cb and Cr colour components.        ph_alf_chroma_idc equal to 1 indicates that the adaptive loop        filter is applied to the Cb colour component. ph_alf_chroma_idc        equal to 2 indicates that the adaptive loop filter is applied to        the Cr colour component. ph_alf_chroma_idc equal to 3 indicates        that the adaptive loop filter is applied to Cb and Cr colour        components. When ph_alf_chroma_idc is not present, it is        inferred to be equal to 0.        ph_alf_aps_id_chroma specifies the adaptation_parameter_set_id        of the ALF APS that the chroma component of the slices        associated with the PH refers to.        The value of alf_chroma_filter_signal_flag of the APS NAL unit        having aps_params_type equal to ALF_APS and        adaptation_parameter_set_id equal to ph_alf_aps_id_chroma shall        be equal to 1.        The TemporalId of the APS NAL unit having aps_params_type equal        to ALF_APS and adaptation_parameter_set_id equal to        ph_alf_aps_id_chroma shall be less than or equal to the        TemporalId of the picture associated with the PH.        ph_cc_alf_cb_enabled_flag equal to 1 specifies that        cross-component filter for Cb colour component is enabled for        all slices associated with the PH and may be applied to Cb        colour component in the slices. ph_cc_alf_cb_enabled_flag equal        to 0 specifies that cross-component filter for Cb colour        component may be disabled for one, or more, or all slices        associated with the PH. When not present,        ph_cc_alf_cb_enabled_flag is inferred to be equal to 0.        ph_cc_alf_cb_aps_id specifies the adaptation_parameter_set_id of        the ALF APS that the Cb colour component of the slices        associated with the PH refers to.        The value of alf_cc_cb_filter_signal_flag of the APS NAL unit        having aps_params_type equal to ALF_APS and        adaptation_parameter_set_id equal to ph_cc_alf_cb_aps_id shall        be equal to 1.        The TemporalId of the APS NAL unit having aps_params_type equal        to ALF_APS and adaptation_parameter_set_id equal to        ph_cc_alf_cb_aps_id shall be less than or equal to the        TemporalId of the picture associated with the PH.        ph_cc_alf_cr_enabled_flag equal to 1 specifies that        cross-component filter for Cr colour component is enabled for        all slices associated with the PH and may be applied to Cr        colour component in the slices. ph_cc_alf_cr_enabled_flag equal        to 0 specifies that cross-component filter for Cr colour        component may be disabled for one, or more, or all slices        associated with the PH. When not present,        ph_cc_alf_cr_enabled_flag is inferred to be equal to 0.        ph_cc_alf_cr_aps_id specifies the adaptation_parameter_set_id of        the ALF APS that the Cr colour component of the slices        associated with the PH refers to.        The value of alf_cc_cr_filter_signal_flag of the APS NAL unit        having aps_params_type equal to ALF_APS and        adaptation_parameter_set_id equal to ph_cc_alf_cr_aps_id shall        be equal to 1.        The TemporalId of the APS NAL unit having aps_params_type equal        to ALF_APS and adaptation_parameter_set_id equal to        ph_cc_alf_cr_aps_id shall be less than or equal to the        TemporalId of the picture associated with the PH.        ph_lmcs_enabled_flag equal to 1 specifies that luma mapping with        chroma scaling is enabled for all slices associated with the PH.        ph_lmcs_enabled_flag equal to 0 specifies that luma mapping with        chroma scaling may be disabled for one, or more, or all slices        associated with the PH. When not present, the value of        ph_lmcs_enabled_flag is inferred to be equal to 0.        ph_lmcs_aps_id specifies the adaptation_parameter_set_id of the        LMCS APS that the slices associated with the PH refers to. The        TemporalId of the APS NAL unit having aps_params_type equal to        LMCS_APS and adaptation_parameter_set_id equal to ph_lmcs_aps_id        shall be less than or equal to the TemporalId of the picture        associated with PH.        ph_chroma_residual_scale_flag equal to 1 specifies that chroma        residual scaling is enabled for the all slices associated with        the PH. ph_chroma_residual_scale_flag equal to 0 specifies that        chroma residual scaling may be disabled for one, or more, or all        slices associated with the PH. When        ph_chroma_residual_scale_flag is not present, it is inferred to        be equal to 0.        ph_scaling_list_present_flag equal to 1 specifies that the        scaling list data used for the slices associated with the PH is        derived based on the scaling list data contained in the        referenced scaling list APS. ph_scaling_list_present_flag equal        to 0 specifies that the scaling list data used for the slices        associated with the PH is set to be equal to 16. When not        present, the value of ph_scaling_list_present_flag is inferred        to be equal to 0.        ph_scaling_list_aps_id specifies the adaptation_parameter_set_id        of the scaling list APS. The TemporalId of the APS NAL unit        having aps_params_type equal to SCALING_APS and        adaptation_parameter_set_id equal to ph_scaling_list_aps_id        shall be less than or equal to the TemporalId of the picture        associated with PH.        ph_virtual_boundaries_present_flag equal to 1 specifies that        information of virtual boundaries is signalled in the PH.        ph_virtual_boundaries_present_flag equal to 0 specifies that        information of virtual boundaries is not signalled in the PH.        When there is one or more than one virtual boundaries signalled        in the PH, the in-loop filtering operations are disabled across        the virtual boundaries in the picture. The in-loop filtering        operations include the deblocking filter, sample adaptive offset        filter, and adaptive loop filter operations. When not present,        the value of ph_virtual_boundaries_present_flag is inferred to        be equal to 0.        It is a requirement of bitstream conformance that, when        subpic_info_present_flag is equal to 1, the value of        ph_virtual_boundaries_present_flag shall be equal to 0.        The variable VirtualBoundariesPresentFlag is derived as follows:    -   VirtualBoundariesPresentFlag=0    -   if(sps_virtual_boundaries_enabled_flag)

VirtualBoundariesPresentFlag=sps_virtual_boundaries_present_flag∥ph_virtual_boundaries_present_flag  (83)

ph_num_ver_virtual_boundaries specifies the number ofph_virtual_boundaries_pos_x[i] syntax elements that are present in thePH. When ph_num_ver_virtual_boundaries is not present, it is inferred tobe equal to 0. The variable NumVerVirtualBoundaries is derived asfollows:

-   -   NumVerVirtualBoundaries=0    -   if(sps_virtual_boundaries_enabled_flag)

NumVerVirtualBoundaries=sps_virtual_boundaries_present_flag?sps_num_ver_virtual_boundaries:ph_num_ver_virtual_boundaries  (84)

ph_virtual_boundaries_pos_x[i] specifies the location of the i-thvertical virtual boundary in units of luma samples divided by 8. Thevalue of ph_virtual_boundaries_pos_x[i] shall be in the range of 1 toCeil(pic_width_in_luma_samples÷8)−1, inclusive.The list VirtualBoundariesPosX[i] for i ranging from 0 toNumVerVirtualBoundaries−1, inclusive, in units of luma samples,specifying the locations of the vertical virtual boundaries, is derivedas follows:

-   -   for(i=0; i<NumVerVirtualBoundaries; i++)

VirtualBoundariesPosX[i]=(sps_virtual_boundaries_present_flag?sps_virtual_boundaries_pos_x[i]:ph_virtual_boundaries_pos_x[i])*8  (85)

The distance between any two vertical virtual boundaries shall begreater than or equal to CtbSizeY luma samples.ph_num_hor_virtual_boundaries specifies the number ofph_virtual_boundaries_pos_y[i] syntax elements that are present in thePH. When ph_num_hor_virtual_boundaries is not present, it is inferred tobe equal to 0.The parameter NumHorVirtualBoundaries is derived as follows:

-   -   NumHorVirtualBoundaries=0    -   if(sps_virtual_boundaries_enabled_flag)

NumHorVirtualBoundaries=sps_virtual_boundaries_present_flag?sps_num_hor_virtual_boundaries:ph_num_hor_virtual_boundaries  (86)

When sps_virtual_boundaries_enabled_flag is equal to 1 andph_virtual_boundaries_present_flag is equal to 1, the sum ofph_num_ver_virtual_boundaries and ph_num_hor_virtual_boundaries shall begreater than 0.ph_virtual_boundaries_pos_y[i] specifies the location of the i-thhorizontal virtual boundary in units of luma samples divided by 8. Thevalue of ph_virtual_boundaries_pos_y[i] shall be in the range of 1 toCeil(pic_height_in_luma_samples÷8)−1, inclusive.The list VirtualBoundariesPosY[i] for i ranging from 0 toNumHorVirtualBoundaries−1, inclusive, in units of luma samples,specifying the locations of the horizontal virtual boundaries, isderived as follows:

-   -   for(i=0; i<NumHorVirtualBoundaries; i++)

VirtualBoundariesPosY[i]=(sps_virtual_boundaries_present_flag?sps_virtual_boundaries_pos_y[i]:ph_virtual_boundaries_pos_y[i])*8  (87)

The distance between any two horizontal virtual boundaries shall begreater than or equal to CtbSizeY luma samples.pic_output_flag affects the decoded picture output and removal processesas specified in Annex C. When pic_output_flag is not present, it isinferred to be equal to 1.partition_constraints_override_flag equal to 1 specifies that partitionconstraint parameters are present in the PH.partition_constraints_override_flag equal to 0 specifies that partitionconstraint parameters are not present in the PH. When not present, thevalue of partition_constraints_override_flag is inferred to be equal to0.ph_log 2_diff_min_qt_min_cb_intra_slice_luma specifies the differencebetween the base 2 logarithm of the minimum size in luma samples of aluma leaf block resulting from quadtree splitting of a CTU and the base2 logarithm of the minimum coding block size in luma samples for lumaCUs in the slices with slice_type equal to 2 (I) associated with the PH.The value of ph_log 2_diff_min_qt_min_cb_intra_slice_luma shall be inthe range of 0 to CtbLog2SizeY−MinCbLog2SizeY, inclusive. When notpresent, the value of ph_log 2_diff_min_qt_min_cb_luma is inferred to beequal to sps_log 2_diff_min_qt_min_cb_intra_slice_luma.ph_max_mtt_hierarchy_depth_intra_slice_luma specifies the maximumhierarchy depth for coding units resulting from multi-type treesplitting of a quadtree leaf in slices with slice_type equal to 2 (I)associated with the PH. The value ofph_max_mtt_hierarchy_depth_intra_slice_luma shall be in the range of 0to 2*(CtbLog2SizeY−MinCbLog2SizeY), inclusive. When not present, thevalue of ph_max_mtt_hierarchy_depth_intra_slice_luma is inferred to beequal to sps_max_mtt_hierarchy_depth_intra_slice_luma.ph_log 2_diff_max_bt_min_qt_intra_slice_luma specifies the differencebetween the base 2 logarithm of the maximum size (width or height) inluma samples of a luma coding block that can be split using a binarysplit and the minimum size (width or height) in luma samples of a lumaleaf block resulting from quadtree splitting of a CTU in slices withslice_type equal to 2 (I) associated with the PH. The value of ph_log2_diff_max_bt_min_qt_intra_slice_luma shall be in the range of 0 toCtbLog2SizeY−MinQtLog2SizeIntraY, inclusive. When not present, the valueof ph_log 2_diff_max_bt_min_qt_intra_slice_luma is inferred to be equalto sps_log 2_diff_max_bt_min_qt_intra_slice_luma.ph_log 2_diff_max_tt_min_qt_intra_slice_luma specifies the differencebetween the base 2 logarithm of the maximum size (width or height) inluma samples of a luma coding block that can be split using a ternarysplit and the minimum size (width or height) in luma samples of a lumaleaf block resulting from quadtree splitting of a CTU in slices withslice_type equal to 2 (I) associated with the PH. The value of ph_log2_diff_max_tt_min_qt_intra_slice_luma shall be in the range of 0 toCtbLog2SizeY−MinQtLog2SizeIntraY, inclusive. When not present, the valueof ph_log 2_diff_max_tt_min_qt_intra_slice_luma is inferred to be equalto sps_log 2_diff_max_tt_min_qt_intra_slice_luma.ph_log 2_diff_min_qt_min_cb_intra_slice_chroma specifies the differencebetween the base 2 logarithm of the minimum size in luma samples of achroma leaf block resulting from quadtree splitting of a chroma CTU withtreeType equal to DUAL_TREE_CHROMA and the base 2 logarithm of theminimum coding block size in luma samples for chroma CUs with treeTypeequal to DUAL_TREE_CHROMA in slices with slice_type equal to 2 (I)associated with the PH. The value of ph_log2_diff_min_qt_min_cb_intra_slice_chroma shall be in the range of 0 toCtbLog2SizeY−MinCbLog2SizeY, inclusive. When not present, the value ofph_log 2_diff_min_qt_min_cb_intra_slice_chroma is inferred to be equalto sps_log 2_diff_min_qt_min_cb_intra_slice_chroma.ph_max_mtt_hierarchy_depth_intra_slice_chroma specifies the maximumhierarchy depth for chroma coding units resulting from multi-type treesplitting of a chroma quadtree leaf with treeType equal toDUAL_TREE_CHROMA in slices with slice_type equal to 2 (I) associatedwith the PH. The value of ph_max_mtt_hierarchy_depth_intra_slice_chromashall be in the range of 0 to 2*(CtbLog2SizeY−MinCbLog2SizeY),inclusive. When not present, the value ofph_max_mtt_hierarchy_depth_intra_slice_chroma is inferred to be equal tosps_max_mtt_hierarchy_depth_intra_slice_chroma.ph_log 2_diff_max_bt_min_qt_intra_slice_chroma specifies the differencebetween the base 2 logarithm of the maximum size (width or height) inluma samples of a chroma coding block that can be split using a binarysplit and the minimum size (width or height) in luma samples of a chromaleaf block resulting from quadtree splitting of a chroma CTU withtreeType equal to DUAL_TREE_CHROMA in slices with slice_type equal to 2(I) associated with the PH. The value of ph_log2_diff_max_bt_min_qt_intra_slice_chroma shall be in the range of 0 toCtbLog2SizeY−MinQtLog2SizeIntraC, inclusive. When not present, the valueof ph_log 2_diff_max_bt_min_qt_intra_slice_chroma is inferred to beequal to sps_log 2_diff_max_bt_min_qt_intra_slice_chroma.ph_log 2_diff_max_tt_min_qt_intra_slice_chroma specifies the differencebetween the base 2 logarithm of the maximum size (width or height) inluma samples of a chroma coding block that can be split using a ternarysplit and the minimum size (width or height) in luma samples of a chromaleaf block resulting from quadtree splitting of a chroma CTU withtreeType equal to DUAL_TREE_CHROMA in slices with slice_type equal to 2(I) associated with the PH. The value of ph_log2_diff_max_tt_min_qt_intra_slice_chroma shall be in the range of 0 toCtbLog2SizeY−MinQtLog2SizeIntraC, inclusive. When not present, the valueof ph_log 2_diff_max_tt_min_qt_intra_slice_chroma is inferred to beequal to sps_log 2_diff_max_tt_min_qt_intra_slice_chromaph_cu_qp_delta_subdiv_intra_slice specifies the maximum cbSubdiv valueof coding units in intra slice that convey cu_qp_delta_abs andcu_qp_delta_sign_flag. The value of ph_cu_qp_delta_subdiv_intra_sliceshall be in the range of 0 to2*(CtbLog2SizeY−MinQtLog2SizeIntraY+ph_max_mtt_hierarchy_depth_intra_slice_luma),inclusive.When not present, the value of ph_cu_qp_delta_subdiv_intra_slice isinferred to be equal to 0.ph_cu_chroma_qp_offset_subdiv_intra_slice specifies the maximum cbSubdivvalue of coding units in intra slice that conveycu_chroma_qp_offset_flag. The value ofph_cu_chroma_qp_offset_subdiv_intra_slice shall be in the range of 0 to2*(CtbLog2SizeY−MinQtLog2SizeIntraY+ph_max_mtt_hierarchy_depth_intra_slice_luma),inclusive.When not present, the value of ph_cu_chroma_qp_offset_subdiv_intra_sliceis inferred to be equal to 0.ph_log 2_diff_min_qt_min_cb_inter_slice specifies the difference betweenthe base 2 logarithm of the minimum size in luma samples of a luma leafblock resulting from quadtree splitting of a CTU and the base 2logarithm of the minimum luma coding block size in luma samples for lumaCUs in the slices with slice_type equal to 0 (B) or 1 (P) associatedwith the PH. The value of ph_log 2_diff_min_qt_min_cb_inter_slice shallbe in the range of 0 to CtbLog2SizeY−MinCbLog2SizeY, inclusive. When notpresent, the value of ph_log 2_diff_min_qt_min_cb_luma is inferred to beequal to sps_log 2_diff_min_qt_min_cb_inter_slice.ph_max_mtt_hierarchy_depth_inter_slice specifies the maximum hierarchydepth for coding units resulting from multi-type tree splitting of aquadtree leaf in slices with slice_type equal to 0 (B) or 1 (P)associated with the PH. The value ofph_max_mtt_hierarchy_depth_inter_slice shall be in the range of 0 to2*(CtbLog2SizeY−MinCbLog2SizeY), inclusive. When not present, the valueof ph_max_mtt_hierarchy_depth_inter_slice is inferred to be equal tosps_max_mtt_hierarchy_depth_inter_slice.ph_log 2_diff_max_bt_min_qt_inter_slice specifies the difference betweenthe base 2 logarithm of the maximum size (width or height) in lumasamples of a luma coding block that can be split using a binary splitand the minimum size (width or height) in luma samples of a luma leafblock resulting from quadtree splitting of a CTU in the slices withslice_type equal to 0 (B) or 1 (P) associated with the PH. The value ofph_log 2_diff_max_bt_min_qt_inter_slice shall be in the range of 0 toCtbLog2SizeY−MinQtLog2SizeInterY, inclusive. When not present, the valueof ph_log 2_diff_max_bt_min_qt_inter_slice is inferred to be equal tosps_log 2_diff_max_bt_min_qt_inter_slice.ph_log 2_diff_max_tt_min_qt_inter_slice specifies the difference betweenthe base 2 logarithm of the maximum size (width or height) in lumasamples of a luma coding block that can be split using a ternary splitand the minimum size (width or height) in luma samples of a luma leafblock resulting from quadtree splitting of a CTU in slices withslice_type equal to 0 (B) or 1 (P) associated with the PH. The value ofph_log 2_diff_max_tt_min_qt_inter_slice shall be in the range of 0 toCtbLog2SizeY−MinQtLog2SizeInterY, inclusive. When not present, the valueof ph_log 2diff_max_tt_min_qt_inter_slice is inferred to be equal tosps_log 2_diff_max_tt_min_qt_inter_slice.ph_cu_qp_delta_subdiv_inter_slice specifies the maximum cbSubdiv valueof coding units that in inter slice convey cu_qp_delta_abs andcu_qp_delta_sign_flag. The value of ph_cu_qp_delta_subdiv_inter_sliceshall be in the range of 0 to2*(CtbLog2SizeY−MinQtLog2SizeInterY+ph_max_mtt_hierarchy_depth_inter_slice),inclusive.When not present, the value of ph_cu_qp_delta_subdiv_inter_slice isinferred to be equal to 0. ph_cu_chroma_qp_offset_subdiv_inter_slicespecifies the maximum cbSubdiv value of coding units in inter slice thatconvey cu_chroma_qp_offset_flag. The value ofph_cu_chroma_qp_offset_subdiv_inter_slice shall be in the range of 0 to2*(CtbLog2SizeY−MinQtLog2SizeInterY+ph_max_mtt_hierarchy_depth_inter_slice),inclusive.When not present, the value of ph_cu_chroma_qp_offset_subdiv_inter_sliceis inferred to be equal to 0. ph_temporal_mvp_enabled_flag specifieswhether temporal motion vector predictors can be used for interprediction for slices associated with the PH. Ifph_temporal_mvp_enabled_flag is equal to 0, the syntax elements of theslices associated with the PH shall be constrained such that no temporalmotion vector predictor is used in decoding of the slices. Otherwise(ph_temporal_mvp_enabled_flag is equal to 1), temporal motion vectorpredictors may be used in decoding of the slices associated with the PH.When not present, the value of ph_temporal_mvp_enabled_flag is inferredto be equal to 0. When no reference picture in the DPB has the samespatial resolution as the current picture, the value ofph_temporal_mvp_enabled_flag shall be equal to 0.The maximum number of subblock-based merging MVP candidates,MaxNumSubblockMergeCand, is derived as follows:

if( sps_affine_enabled_flag )  MaxNumSubblockMergeCand = 5 − (88) five_minus_max_num_subblock_merge_cand  else  MaxNumSubblockMergeCand =sps_sbtmvp_enabled_flag &&  ph_temporal_mvp_enable_flagThe value of MaxNumSubblockMergeCand shall be in the range of 0 to 5,inclusive. ph_collocated_from_I0_flag equal to 1 specifies that thecollocated picture used for temporal motion vector prediction is derivedfrom reference picture list 0. ph_collocated_from_I0_flag equal to 0specifies that the collocated picture used for temporal motion vectorprediction is derived from reference picture list 1.ph_collocated_ref_idx specifies the reference index of the collocatedpicture used for temporal motion vector prediction.When ph_collocated_from_I0_flag is equal to 1, ph_collocated_ref_idxrefers to an entry in reference picture list 0, and the value ofph_collocated_ref_idx shall be in the range of 0 tonum_ref_entries[0][RplsIdx[0]]−1, inclusive.When ph_collocated_from_I0_flag is equal to 0, ph_collocated_ref_idxrefers to an entry in reference picture list 1, and the value ofph_collocated_ref_idx shall be in the range of 0 tonum_ref_entries[1][RplsIdx[1]]−1, inclusive. When not present, the valueof ph_collocated_ref_idx is inferred to be equal to 0.mvd_I1_zero_flag equal to 1 indicates that the mvd_coding(x0, y0, 1)syntax structure is not parsed and MvdL1[x0][y0][compIdx] andMvdCpL1[x0][y0][cpIdx][compIdx] are set equal to 0 for compIdx=0 . . . 1and cpIdx=0 . . . 2. mvd_l1_zero_flag equal to 0 indicates that themvd_coding(x0, y0, 1) syntax structure is parsed.ph_fpel_mmvd_enabled_flag equal to 1 specifies that merge mode withmotion vector difference uses integer sample precision in the slicesassociated with the PH. ph_fpel_mmvd_enabled_flag equal to 0 specifiesthat merge mode with motion vector difference can use fractional sampleprecision in the slices associated with the PH. When not present, thevalue of ph_fpel_mmvd_enabled_flag is inferred to be 0.ph_disable_bdof_flag equal to 1 specifies that bi-directional opticalflow inter prediction based inter bi-prediction is disabled in theslices associated with the PH. ph_disable_bdof_flag equal to 0 specifiesthat bi-directional optical flow inter prediction based interbi-prediction may or may not be enabled in the slices associated withthe PH.When ph_disable_bdof_flag is not present, the following applies:

-   -   If sps_bdof_enabled_flag is equal to 1, the value of        ph_disable_bdof_flag is inferred to be equal to 0.    -   Otherwise (sps_bdof_enabled_flag is equal to 0), the value of        ph_disable_bdof_flag is inferred to be equal to 1.        ph_disable_dmvr_flag equal to 1 specifies that decoder motion        vector refinement based inter bi-prediction is disabled in the        slices associated with the PH. ph_disable_dmvr_flag equal to 0        specifies that decoder motion vector refinement based inter        bi-prediction may or may not be enabled in the slices associated        with the PH.        When ph_disable_dmvr_flag is not present, the following applies:    -   If sps_dmvr_enabled_flag is equal to 1, the value of        ph_disable_dmvr_flag is inferred to be equal to 0.    -   Otherwise (sps_dmvr_enabled_flag is equal to 0), the value of        ph_disable_dmvr_flag is inferred to be equal to 1.        ph_disable_prof_flag equal to 1 specifies that prediction        refinement with optical flow is disabled in the slices        associated with the PH. ph_disable_prof_flag equal to 0        specifies that prediction refinement with optical flow may or        may not be enabled in the slices associated with the PH.        When ph_disable_prof_flag is not present, the following applies:    -   If sps_affine_prof_enabled_flag is equal to 1, the value of        ph_disable_prof_flag is inferred to be equal to 0.    -   Otherwise (sps_affine_prof_enabled_flag is equal to 0), the        value of ph_disable_prof_flag is inferred to be equal to 1.        ph_qp_delta specifies the initial value of Qp_(Y) to be used for        the coding blocks in the picture until modified by the value of        CuQpDeltaVal in the coding unit layer.        When qp_delta_info_in_ph_flag is equal to 1, the initial value        of the Qp_(Y) quantization parameter for all slices of the        picture, SliceQp_(Y), is derived as follows:

SliceQp_(Y)=26+init_qp_minus26+ph_qp_delta  (89)

The value of SliceQp_(Y) shall be in the range of −QpBdOffset to +63,inclusive.ph_joint_cbcr_sign_flag specifies whether, in transform units withtu_joint_cbcr_residual_flag[x0][y0] equal to 1, the collocated residualsamples of both chroma components have inverted signs. Whentu_joint_cbcr_residual_flag[x0][y0] equal to 1 for a transform unit,ph_joint_cbcr_sign_flag equal to 0 specifies that the sign of eachresidual sample of the Cr (or Cb) component is identical to the sign ofthe collocated Cb (or Cr) residual sample and ph_joint_cbcr_sign_flagequal to 1 specifies that the sign of each residual sample of the Cr (orCb) component is given by the inverted sign of the collocated Cb (or Cr)residual sample.ph_sao_luma_enabled_flag equal to 1 specifies that SAO is enabled forthe luma component in all slices associated with the PH;ph_sao_luma_enabled_flag equal to 0 specifies that SAO for the lumacomponent may be disabled for one, or more, or all slices associatedwith the PH. When ph_sao_luma_enabled_flag is not present, it isinferred to be equal to 0.ph_sao_chroma_enabled_flag equal to 1 specifies that SAO is enabled forthe chroma component in all slices associated with the PH;ph_sao_chroma_enabled_flag equal to 0 specifies that SAO for chromacomponent may be disabled for one, or more, or all slices associatedwith the PH. When ph_sao_chroma_enabled_flag is not present, it isinferred to be equal to 0.ph_dep_quant_enabled_flag equal to 0 specifies that dependentquantization is disabled for the current picture.ph_dep_quant_enabled_flag equal to 1 specifies that dependentquantization is enabled for the current picture. Whenph_dep_quant_enabled_flag is not present, it is inferred to be equal to0.pic_sign_data_hiding_enabled_flag equal to 0 specifies that sign bithiding is disabled for the current picture.pic_sign_data_hiding_enabled_flag equal to 1 specifies that sign bithiding is enabled for the current picture. Whenpic_sign_data_hiding_enabled_flag is not present, it is inferred to beequal to 0.ph_deblocking_filter_override_flag equal to 1 specifies that deblockingparameters are present in the PH. ph_deblocking_filter_override_flagequal to 0 specifies that deblocking parameters are not present in thePH. When not present, the value of ph_deblocking_filter_override_flag isinferred to be equal to 0.ph_deblocking_filter_disabled_flag equal to 1 specifies that theoperation of the deblocking filter is not applied for the slicesassociated with the PH. ph_deblocking_filter_disabled_flag equal to 0specifies that the operation of the deblocking filter is applied for theslices associated with the PH. When ph_deblocking_filter_disabled_flagis not present, it is inferred to be equal topps_deblocking_filter_disabled_flag.ph_beta_offset_div2 and ph_tc_offset_div2 specify the deblockingparameter offsets for β and tC (divided by 2) that are applied to theluma component for the slices associated with the PH. The values ofph_beta_offset_div2 and ph_tc_offset_div2 shall both be in the range of−12 to 12, inclusive. When not present, the values ofph_beta_offset_div2 and ph_tc_offset_div2 are inferred to be equal topps_beta_offset_div2 and pps_tc_offset_div2, respectively.ph_cb_beta_offset_div2 and ph_cb_tc_offset_div2 specify the deblockingparameter offsets for β and tC (divided by 2) that are applied to the Cbcomponent for the slices associated with the PH. The values ofph_cb_beta_offset_div2 and ph_cb_tc_offset_div2 shall both be in therange of −12 to 12, inclusive. When not present, the values ofph_cb_beta_offset_div2 and ph_cb_tc_offset_div2 are inferred to be equalto pps_cb_beta_offset_div2 and pps_cb_tc_offset_div2, respectively.ph_cr_beta_offset_div2 and ph_cr_tc_offset_div2 specify the deblockingparameter offsets for β and tC (divided by 2) that are applied to the Crcomponent for the slices associated with the PH. The values ofph_cr_beta_offset_div2 and ph_cr_tc_offset_div2 shall both be in therange of −12 to 12, inclusive. When not present, the values ofph_cr_beta_offset_div2 and ph_cr_tc_offset_div2 are inferred to be equalto pps_cr_beta_offset_div2 and pps_cr_tc_offset_div2, respectively.ph_extension_length specifies the length of the PH extension data inbytes, not including the bits used for signalling ph_extension_lengthitself. The value of ph_extension_length shall be in the range of 0 to256, inclusive. When not present, the value of ph_extension_length isinferred to be equal to 0.ph_extension_data_byte may have any value. Decoders conforming to thisversion of this Specification shall ignore the value ofph_extension_data_byte. Its value does not affect decoder conformance toprofiles specified in this version of specification.

3.4. SH Syntax and Semantics

In the latest VVC draft text, the SH syntax and semantics are asfollows:

Descriptor slice_header( ) {  picture_header_in_slice_header_flag u(1) if( picture_header_in_slice_header_flag )   picture_header_structure( ) if( subpic_info_present_flag )   slice_subpic_id u(v)  if( (rect_slice_flag && NumSlicesInSubpic[ CurrSubpicIdx ] > 1 ) | |    (!rect_slice_flag && NumTilesInPic > 1 ) )   slice_address u(v)  for( i =0; i < NumExtraShBits; i++ )   sh_extra_bit[ i ] u(1)  if(!rect_slice_flag && NumTilesInPic > 1 )   num_tiles_in_slice_minus1ue(v)  if( ph_inter_slice_allowed_flag )   slice_type ue(v)  if(sps_alf_enabled_flag && !alf_info_in_ph flag ) {  slice_alf_enabled_flag u(1)   if( slice_alf_enabled_flag ) {   slice_num_alf_aps_ids_luma u(3)    for( i = 0; i <slice_num_alf_aps_ids_luma; i++ )     slice_alf_aps_id_luma[ i ] u(3)   if( ChromaArrayType != 0 )     slice_alf_chroma_idc u(2)    if(slice_alf_chroma_idc )     slice_alf_aps_id_chroma u(3)    if(sps_ccalf_enabled_flag ) {     slice_cc_alf_cb_enabled_flag u(1)     if(slice_cc_alf_cb_enabled_flag )      slice_cc_alf_cb_aps_id u(3)    slice_cc_alf_cr_enabled_flag u(1)     if(slice_cc_alf_cr_enabled_flag )      slice_cc_alf_cr_aps_id u(3)    }   } }  if( separate_colour_plane_flag = = 1 )   colour_plane_id u(2)  if(!rpl_info_in_ph_flag && ( ( nal_unit_type != IDR_W_RADL && nal_unit_type!=    IDR_N_LP ) | | sps_idr_rpl_present_flag ) )   ref_pic_lists( ) if( ( rpl_info_in_ph_flag ( ( nal_unit_type != IDR_W_RADL &&nal_unit_type !=    IDR_N_LP ) | | sps_idr_rpl_present_flag ) ) &&    (slice_type != I && num_ref_entries[ 0 ][ RplsIdx[ 0 ] ] > 1 ) | |    (slice_type = = B && num_ref_entries[ 1 ][ RplsIdx[ 1 ] ] > 1 ) ) {  num_ref_idx_active_override_flag u(1)   if(num_ref_idx_active_override_flag )    for( i = 0; i < ( slice_type = = B? 2: 1); i++ )     if( num_ref_entries[ i ][ RplsIdx[ i ] ] > 1 )     num_ref_idx_active_minus1[ i ] ue(v)  }  if( slice_type != I ) {  if( cabac_init_present_flag )    cabac_init_flag u(1)   if(ph_temporal_mvp_enabled_flag && !rpl_info_in_ph_flag ) {    if(slice_type = = B )     slice_collocated_from_10_flag u(1)    if( (slice_collocated_from_10_flag && NumRefIdxActive [ 0 ] > 1 ) | |      (! slice_collocated_from_10_flag && NumRefIdxActive [ 1 ] > 1) )    slice_collocated_ref_idx ue(v)   }   if( !wp_info_in_ph_flag && ( (pps_weighted_pred_flag && slice_type = = P ) | |    (pps_weighted_bipred_flag && slice_type = = B ) ) )   pred_weight_table( )  }  if( !qp_delta_info_in_ph_flag )  slice_qp_delta se(v)  if( pps_slice_chroma_qp_offsets_present_flag ) {  slice_cb_qp_offset se(v)   slice_cr_qp_offset se(v)   if(sps_joint_cbcr_enabled_flag )    slice_joint_cbcr_qp_offset se(v)  } if( pps_cu_chroma_qp_offset_list_enabled_flag )  cu_chroma_qp_offset_enabled_flag u(1)  if( sps_sao_enabled_flag &&!sao_info_in_ph_flag ) {   slice_sao_luma_flag u(1)   if(ChromaArrayType != 0 )    slice_sao_chroma_flag u(1)  }  if(deblocking_filter_override_enabled_flag && !dbf_info_in_ph_flag )  slice_deblocking_filter_override_flag u(1)  if(slice_deblocking_filter_override_flag ) {  slice_deblocking_filter_disabled_flag u(1)   if(!slice_deblocking_filter_disabled_flag ) {    slice_beta_offset_div2se(v)    slice_tc_offset_div2 se(v)    slice_cb_beta_offset_div2 se(v)   slice_cb_tc_offset_div2 se(v)    slice_cr_beta_offset_div2 se(v)   slice_cr_tc_offset_div2 se(v)   }  } slice_ts_residual_coding_disabled_flag u(1)  if( ph_lmcs_enabled_flag )  slice_lmcs_enabled_flag u(1)  if( ph_scaling_list_enabled_flag )  slice_scaling_list_present_flag u(1)  if( NumEntryPoints > 0 ) {  offset_len_minus1 ue(v)   for( i = 0; i < NumEntryPoints; i++ )   entry_point_offset_minus1[ i ] u(v)  }  if(slice_header_extension_present_flag ) {   slice_header_extension_lengthue(v)   for( i = 0; i < slice_header_extension_length; i++)   slice_header_extension_data_byte[ i ] u(8)  }  byte_alignment( ) }The variable CuQpDeltaVal, specifying the difference between a lumaquantization parameter for the coding unit containing cu_qp_delta_absand its prediction, is set equal to 0. The variables CuQpOffset_(Cb),CuQpOffset_(Cr), and CuQpOffset_(CbCr), specifying values to be usedwhen determining the respective values of the Qp′ct, Qp′_(Cr), andQp′_(CbCr) quantization parameters for the coding unit containingcu_chroma_qp_offset_flag, are all set equal to 0.picture_header_in_slice_header_flag equal to 1 specifies that the PHsyntax structure is present in the slice header.picture_header_in_slice_header_flag equal to 0 specifies that the PHsyntax structure is not present in the slice header. It is a requirementof bitstream conformance that the value ofpicture_header_in_slice_header_flag shall be the same in all codedslices in a CLVS.When picture_header_in_slice_header_flag is equal to 1 for a codedslice, it is a requirement of bitstream conformance that no VCL NAL unitwith nal_unit_type equal to PH_NUT shall be present in the CLVS.When picture_header_in_slice_header_flag is equal to 0, all coded slicesin the current picture shall have picture_header_in_slice_header_flag isequal to 0, and the current PU shall have a PH NAL unit.slice_subpic_id specifies the subpicture ID of the subpicture thatcontains the slice. If slice_subpic_id is present, the value of thevariable CurrSubpicIdx is derived to be such thatSubpicIdVal[CurrSubpicIdx] is equal to slice_subpic_id. Otherwise(slice_subpic_id is not present), CurrSubpicIdx is derived to be equalto 0. The length of slice_subpic_id is sps_subpic_id_len_minus1+1 bits.slice_address specifies the slice address of the slice. When notpresent, the value of slice_address is inferred to be equal to 0. Whenrect_slice_flag is equal to 1 and NumSlicesInSubpic[CurrSubpicIdx] isequal to 1, the value of slice_address is inferred to be equal to 0.If rect_slice_flag is equal to 0, the following applies:

-   -   The slice address is the raster scan tile index.    -   The length of slice_address is Ceil(Log 2 (NumTilesInPic)) bits.    -   The value of slice_address shall be in the range of 0 to        NumTilesInPic−1, inclusive.        Otherwise (rect_slice_flag is equal to 1), the following        applies:    -   The slice address is the subpicture-level slice index of the        slice.    -   The length of slice_address is Ceil(Log        2(NumSlicesInSubpic[CurrSubpicIdx])) bits.    -   The value of slice_address shall be in the range of 0 to        NumSlicesInSubpic[CurrSubpicIdx]−1, inclusive.        It is a requirement of bitstream conformance that the following        constraints apply:    -   If rect_slice_flag is equal to 0 or subpic_info_present_flag is        equal to 0, the value of slice_address shall not be equal to the        value of slice_address of any other coded slice NAL unit of the        same coded picture.    -   Otherwise, the pair of slice_subpic_id and slice_address values        shall not be equal to the pair of slice_subpic_id and        slice_address values of any other coded slice NAL unit of the        same coded picture.    -   The shapes of the slices of a picture shall be such that each        CTU, when decoded, shall have its entire left boundary and        entire top boundary consisting of a picture boundary or        consisting of boundaries of previously decoded CTU(s).        sh_extra_bit[i] may be equal to 1 or 0. Decoders conforming to        this version of this Specification shall ignore the value of        sh_extra_bit[i]. Its value does not affect decoder conformance        to profiles specified in this version of specification.        num_tiles_in_slice_minus1 plus 1, when present, specifies the        number of tiles in the slice. The value of        num_tiles_in_slice_minus1 shall be in the range of 0 to        NumTilesInPic−1, inclusive.        The variable NumCtusInCurrSlice, which specifies the number of        CTUs in the current slice, and the list CtbAddrInCurrSlice[i],        for i ranging from 0 to NumCtusInCurrSlice−1, inclusive,        specifying the picture raster scan address of the i-th CTB        within the slice, are derived as follows:

if( rect_slice_flag ) {  picLevelSliceIdx = slice_address  for( j = 0; j< CurrSubpicIdx; j++ )   picLevelSliceIdx += NumSlicesInSubpic[ j ] NumCtusInCurrSlice = NumCtusInSlice[ picLevelSliceIdx ]  for( i = 0; i< NumCtusInCurrSlice; i++ )   CtbAddrInCurrSlice[ i ] = CtbAddrInSlice[(117)   picLevelSliceIdx ][ i ] } else {  NumCtusInCurrSlice = 0  for(tileIdx = slice_address; tileIdx <=  slice_address +num_tiles_in_slice_minus1; tileIdx++ ) {   tileX = tileIdx %NumTileColumns   tileY = tileIdx / NumTileColumns   for( ctbY =tileRowBd[ tileY ]; ctbY < tileRowBd[ tileY + 1 ];   ctbY++ ) {    for(ctbX = tileColBd[ tileX ]; ctbX < tileColBd[ tileX + 1 ];    ctbX++ ) {    CtbAddrInCurrSlice[ NumCtusInCurrSlice ] = ctbY *    PicWidthInCtb + ctbX     NumCtusInCurrSlice++    }   }  } }The variables SubpicLeftBoundaryPos, SubpicTopBoundaryPos,SubpicRightBoundaryPos, and SubpicBotBoundaryPos are derived as follows:

if( subpic_treated_as_pic_flag[ CurrSubpicIdx ] ) { SubpicLeftBoundaryPos = subpic_ctu_top_left_x[  CurrSubpicIdx ] *CtbSizeY  SubpicRightBoundaryPos = Min(  pic_width_max_in_luma_samples −1,   ( subpic_ctu_top_left_x[ CurrSubpicIdx ] +   subpic_width_minus1[CurrSubpicIdx ] + 1 ) * CtbSizeY − 1 )  SubpicTopBoundaryPos =subpic_ctu_top_left_y[ (118)  CurrSubpicIdx ] *CtbSizeY SubpicBotBoundaryPos = Min(  pic_height_max_in_luma_samples − 1,   (subpic_ctu_top_left_y[ CurrSubpicIdx ] +   subpic_height_minus1[CurrSubpicIdx ] + 1 ) * CtbSizeY − 1 ) }slice_type specifies the coding type of the slice according to Table 9.

TABLE 9 Name association to slice_type slice_type Name of slice_type 0 B(B slice) 1 P (P slice) 2 I (I slice)When not present, the value of slice_type is inferred to be equal to 2.When ph_intra_slice_allowed_flag is equal to 0, the value of slice_typeshall be equal to 0 or 1. When nal_unit_type is in the range ofIDR_W_RADL to CRA_NUT, inclusive, andvps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id]] is equal to 1,slice_type shall be equal to 2.The variables MinQtLog2SizeY, MinQtLog2SizeC, MinQtSizeY, MinQtSizeC,MaxBtSizeY, MaxBtSizeC, MinBtSizeY, MaxTtSizeY, MaxTtSizeC, MinTtSizeY,MaxMttDepthY and MaxMttDepthC are derived as follows:

-   -   If slice_type equal to 2 (I), the following applies:

MinQtLog2SizeY=MinCbLog2SizeY+ph_log2_diff_min_qt_min_cb_intra_slice_luma  (119)

MinQtLog2SizeC=MinCbLog2SizeY+ph_log2_diff_min_qt_min_cb_intra_slice_chroma  (120)

MaxBtSizeY=1<<(MinQtLog2SizeY+ph_log2_diff_max_bt_min_qt_intra_slice_luma)  (121)

MaxBtSizeC=1<<(MinQtLog2SizeC+ph_log2_diff_max_bt_min_qt_intra_slice_chroma)  (122)

MaxTtSizeY=1<<(MinQtLog2SizeY+ph_log2_diff_max_tt_min_qt_intra_slice_luma)  (123)

MaxTtSizeC=1<<(MinQtLog2SizeC+ph log2_diff_max_tt_min_qt_intra_slice_chroma)  (124)

MaxMttDepthY=ph_max_mtt_hierarchy_depth_intra_slice_luma  (125)

MaxMttDepthC=ph_max_mtt_hierarchy_depth_intra_slice_chroma  (126)

CuQpDeltaSubdiv=ph_cu_qp_delta_subdiv_intra_slice  (127)

CuChromaQpOffsetSubdiv=ph_cu_chroma_qp_offset_subdiv_intra_slice  (128)

-   -   Otherwise (slice_type equal to 0 (B) or 1 (P)), the following        applies:

MinQtLog2SizeY=MinCbLog2SizeY+ph_log2_diff_min_qt_min_cb_inter_slice  (129)

MinQtLog2SizeC=MinCbLog2SizeY+ph_log2_diff_min_qt_min_cb_inter_slice  (130)

MaxBtSizeY=1<<(MinQtLog2SizeY+ph log2_diff_max_bt_min_qt_inter_slice)  (131)

MaxBtSizeC=1<<(MinQtLog2SizeC+ph_log2_diff_max_bt_min_qt_inter_slice)  (132)

MaxTtSizeY=1<<(MinQtLog2SizeY+ph_log2_diff_max_tt_min_qt_inter_slice)  (133)

MaxTtSizeC=1<<(MinQtLog2SizeC+ph log2_diff_max_tt_min_qt_inter_slice)  (134)

MaxMttDepthY=ph_max_mtt_hierarchy_depth_inter_slice  (135)

MaxMttDepthC=ph_max_mtt_hierarchy_depth_inter_slice  (136)

CuQpDeltaSubdiv=ph_cu_qp_delta_subdiv_inter_slice  (137)

CuChromaQpOffsetSubdiv=ph_cu_chroma_qp_offset_subdiv_inter_slice  (138)

-   -   The following applies:

MinQtSizeY=1<<MinQtLog2SizeY  (139)

MinQtSizeC=1<<MinQtLog2SizeC  (140)

MinBtSizeY=1<<MinCbLog2SizeY  (141)

MinTtSizeY=1<<MinCbLog2SizeY  (142)

slice_alf_enabled_flag equal to 1 specifies that adaptive loop filter isenabled and may be applied to Y, Cb, or Cr colour component in a slice.slice_alf_enabled_flag equal to 0 specifies that adaptive loop filter isdisabled for all colour components in a slice. When not present, thevalue of slice_alf_enabled_flag is inferred to be equal toph_alf_enabled_flag.slice_num_alf_aps_ids_luma specifies the number of ALF APSs that theslice refers to. When slice_alf_enabled_flag is equal to 1 andslice_num_alf_aps_ids_luma is not present, the value ofslice_num_alf_aps_ids_luma is inferred to be equal to the value ofph_num_alf_aps_ids_luma.slice_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id ofthe i-th ALF APS that the luma component of the slice refers to. TheTemporalId of the APS NAL unit having aps_params_type equal to ALF_APSand adaptation_parameter_set_id equal to slice_alf_aps_id_luma[i] shallbe less than or equal to the TemporalId of the coded slice NAL unit.When slice_alf_enabled_flag is equal to 1 and slice_alf_aps_id_luma[i]is not present, the value of slice_alf_aps_id_luma[i] is inferred to beequal to the value of ph_alf_aps_id_luma[i].The value of alf_luma_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto slice_alf_aps_id_luma[i] shall be equal to 1.slice_alf_chroma_idc equal to 0 specifies that the adaptive loop filteris not applied to Cb and Cr colour components. slice_alf_chroma_idcequal to 1 indicates that the adaptive loop filter is applied to the Cbcolour component. slice_alf_chroma_idc equal to 2 indicates that theadaptive loop filter is applied to the Cr colour component.slice_alf_chroma_idc equal to 3 indicates that the adaptive loop filteris applied to Cb and Cr colour components.When slice_alf_chroma_idc is not present, it is inferred to be equal toph_alf_chroma_idc.slice_alf_aps_id_chroma specifies the adaptation_parameter_set_id of theALF APS that the chroma component of the slice refers to. The TemporalIdof the APS NAL unit having aps_params_type equal to ALF_APS andadaptation_parameter_set_id equal to slice_alf_aps_id_chroma shall beless than or equal to the TemporalId of the coded slice NAL unit. Whenslice_alf_enabled_flag is equal to 1 and slice_alf_aps_id_chroma is notpresent, the value of slice_alf_aps_id_chroma is inferred to be equal tothe value of ph_alf_aps_id_chroma.The value of alf_chroma_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto slice_alf_aps_id_chroma shall be equal to 1.slice_cc_alf_cb_enabled_flag equal to 0 specifies that thecross-component filter is not applied to the Cb colour component.slice_cc_alf_cb_enabled_flag equal to 1 indicates that thecross-component filter is enabled and may be applied to the Cb colourcomponent. When slice_cc_alf_cb_enabled_flag is not present, it isinferred to be equal to ph_cc_alf_cb_enabled_flag.slice_cc_alf_cb_aps_id specifies the adaptation_parameter_set_id thatthe Cb colour component of the slice refers to. The TemporalId of theAPS NAL unit having aps_params_type equal to ALF_APS andadaptation_parameter_set_id equal to slice_cc_alf_cb_aps_id shall beless than or equal to the TemporalId of the coded slice NAL unit. Whenslice_cc_alf_cb_enabled_flag is equal to 1 and slice_cc_alf_cb_aps_id isnot present, the value of slice_cc_alf_cb_aps_id is inferred to be equalto the value of ph_cc_alf_cb_aps_id.The value of alf_cc_cb_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto slice_cc_alf_cb_aps_id shall be equal to 1.slice_cc_alf_cr_enabled_flag equal to 0 specifies that thecross-component filter is not applied to the Cr colour component.slice_cc_alf_cb_enabled_flag equal to 1 indicates that thecross-component adaptive loop filter is enabled and may be applied tothe Cr colour component. When slice_cc_alf_cr_enabled_flag is notpresent, it is inferred to be equal to ph_cc_alf_cr_enabled_flag.slice_cc_alf_cr_aps_id specifies the adaptation_parameter_set_id thatthe Cr colour component of the slice refers to. The TemporalId of theAPS NAL unit having aps_params_type equal to ALF_APS andadaptation_parameter_set_id equal to slice_cc_alf_cr_aps_id shall beless than or equal to the TemporalId of the coded slice NAL unit. Whenslice_cc_alf_cr_enabled_flag is equal to 1 and slice_cc_alf_cr_aps_id isnot present, the value of slice_cc_alf_cr_aps_id is inferred to be equalto the value of ph_cc_alf_cr_aps_id.The value of alf_cc_cr_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto slice_cc_alf_cr_aps_id shall be equal to 1.colour_plane_id identifies the colour plane associated with the currentslice when separate_colour_plane_flag is equal to 1. The value ofcolour_plane_id shall be in the range of 0 to 2, inclusive.colour_plane_id values 0, 1 and 2 correspond to the Y, Cb and Cr planes,respectively. The value 3 of colour_plane_id is reserved for future useby ITU-T|ISO/IEC.

-   -   NOTE 1—There is no dependency between the decoding processes of        different colour planes of one picture.        num_ref_idx_active_override_flag equal to 1 specifies that the        syntax element num_ref_idx_active_minus1[0] is present for P and        B slices and the syntax element num_ref_idx_active_minus1[1] is        present for B slices. num_ref_idx_active_override_flag equal to        0 specifies that the syntax elements        num_ref_idx_active_minus1[0] and num_ref_idx_active_minus1[1]        are not present. When not present, the value of        num_ref_idx_active_override_flag is inferred to be equal to 1.        num_ref_idx_active_minus1[i] is used for the derivation of the        variable NumRefIdxActive[i] as specified by Equation 143. The        value of num_ref_idx_active_minus1[i] shall be in the range of 0        to 14, inclusive.        For i equal to 0 or 1, when the current slice is a B slice,        num_ref_idx_active_override_flag is equal to 1, and        num_ref_idx_active_minus1[i] is not present,        num_ref_idx_active_minus1[i] is inferred to be equal to 0. When        the current slice is a P slice, num_ref_idx_active_override_flag        is equal to 1, and num_ref_idx_active_minus1[0] is not present,        num_ref_idx_active_minus1[0] is inferred to be equal to 0.        The variable NumRefIdxActive[i] is derived as follows:

for( i = 0; i < 2; i++ ) {  if( slice_type = = B | | ( slice_type = = P&& i = = 0 ) ) {   if( num_ref_idx_active_override_flag )   NumRefIdxActive[ i ] = (143)    num_ref_idx_active_minus1[ i ] + 1  else {    if( num_ref_entries[ i ][ RplsIdx[ i ] ] >=   num_ref_idx_default_active_minus1[ i ] + 1 )     NumRefIdxActive[ i ]=     num_ref_idx_default_active_minus1[ i ] + 1    else    NumRefIdxActive[ i ] = num_ref_entries[ i ][ RplsIdx[ i ] ]   }  }else /* slice_type = = I | | ( slice_type = = P && i = = 1 ) */  NumRefIdxActive[ i ] = 0 }The value of NumRefIdxActive[i]−1 specifies the maximum reference indexfor reference picture list i that may be used to decode the slice. Whenthe value of NumRefIdxActive[i] is equal to 0, no reference index forreference picture list i may be used to decode the slice.When the current slice is a P slice, the value of NumRefIdxActive[0]shall be greater than 0.When the current slice is a B slice, both NumRefIdxActive[0] andNumRefIdxActive[1] shall be greater than 0.cabac_init_flag specifies the method for determining the initializationtable used in the initialization process for context variables. Whencabac_init_flag is not present, it is inferred to be equal to 0.slice_collocated_from_I0_flag equal to 1 specifies that the collocatedpicture used for temporal motion vector prediction is derived fromreference picture list 0. slice_collocated_from_I0_flag equal to 0specifies that the collocated picture used for temporal motion vectorprediction is derived from reference picture list 1.When slice_type is equal to B or P, ph_temporal_mvp_enabled_flag isequal to 1, and slice_collocated_from_I0_flag is not present, thefollowing applies:

-   -   If rpl_info_in_ph_flag is equal to 1,        slice_collocated_from_I0_flag is inferred to be equal to        ph_collocated_from_I0_flag.    -   Otherwise (rpl_info_in_ph_flag is equal to 0 and slice_type is        equal to P), the value of slice_collocated_from_I0_flag is        inferred to be equal to 1.        slice_collocated_ref_idx specifies the reference index of the        collocated picture used for temporal motion vector prediction.        When slice_type is equal to P or when slice_type is equal to B        and slice_collocated_from_I0_flag is equal to 1,        slice_collocated_ref_idx refers to an entry in reference picture        list 0, and the value of slice_collocated_ref_idx shall be in        the range of 0 to NumRefIdxActive[0]−1, inclusive.        When slice_type is equal to B and slice_collocated_from_I0_flag        is equal to 0, slice_collocated_ref_idx refers to an entry in        reference picture list 1, and the value of        slice_collocated_ref_idx shall be in the range of 0 to        NumRefIdxActive[1]−1, inclusive.        When slice_collocated_ref_idx is not present, the following        applies:    -   If rpl_info_in_ph_flag is equal to 1, the value of        slice_collocated_ref_idx is inferred to be equal to        ph_collocated_ref_idx.    -   Otherwise (rpl_info_in_ph_flag is equal to 0), the value of        slice_collocated_ref_idx is inferred to be equal to 0.        It is a requirement of bitstream conformance that the picture        referred to by slice_collocated_ref_idx shall be the same for        all slices of a coded picture.        It is a requirement of bitstream conformance that the values of        pic_width_in_luma_samples and pic_height_in_luma_samples of the        reference picture referred to by slice_collocated_ref_idx shall        be equal to the values of pic_width_in_luma_samples and        pic_height_in_luma_samples, respectively, of the current        picture, and RprConstraintsActive[slice_collocated_from_I0_flag        ? 0:1][slice_collocated_ref_idx] shall be equal to 0.        slice_qp_delta specifies the initial value of Qp_(Y) to be used        for the coding blocks in the slice until modified by the value        of CuQpDeltaVal in the coding unit layer.        When qp_delta_info_in_ph_flag is equal to 0, the initial value        of the Qp_(Y) quantization parameter for the slice, SliceQp_(Y),        is derived as follows:

SliceQp_(Y)=26+init_qp_minus26+slice_qp_delta  (144)

The value of SliceQp_(Y) shall be in the range of −QpBdOffset to +63,inclusive.When either of the following conditions is true:

-   -   The value of wp_info_in_ph_flag is equal to 1,        pps_weighted_pred_flag is equal to 1, and slice_type is equal to        P.    -   The value of wp_info_in_ph_flag is equal to 1,        pps_weighted_bipred_flag is equal to 1, and slice_type is equal        to B.        the following applies:    -   The value of NumRefIdxActive[0] shall be less than or equal to        the value of NumWeightsL0.    -   For each reference picture index RefPicList[0][i] for i in the        range of 0 to NumRefIdxActive[0]−1, inclusive, the luma weight,        Cb weight, and Cr weight that apply to the reference picture        index are LumaWeightL0[i], ChromaWeightL0[0][i], and        ChromaWeightL0[1][i], respectively.        When wp_info_in_ph_flag is equal to 1, pps_weighted_bipred_flag        is equal to 1, and slice_type is equal to B, the following        applies:    -   The value of NumRefIdxActive[1] shall be less than or equal to        the value of NumWeightsL1.    -   For each reference picture index RefPicList[1][i] for i in the        range of 0 to NumRefIdxActive[1]−1, inclusive, the luma weight,        Cb weight, and Cr weight that apply to the reference picture        index are LumaWeightL0[i], ChromaWeightL1[0][i], and        ChromaWeightL1[1][i], respectively.        slice_cb_qp_offset specifies a difference to be added to the        value of pps_cb_qp_offset when determining the value of the        Qp′_(Cb) quantization parameter. The value of slice_cb_qp_offset        shall be in the range of −12 to +12, inclusive.        When slice_cb_qp_offset is not present, it is inferred to be        equal to 0. The value of pps_cb_qp_offset+slice_cb_qp_offset        shall be in the range of −12 to +12, inclusive.        slice_cr_qp_offset specifies a difference to be added to the        value of pps_cr_qp_offset when determining the value of the        Qp′_(Cr) quantization parameter. The value of slice_cr_qp_offset        shall be in the range of −12 to +12, inclusive. When        slice_cr_qp_offset is not present, it is inferred to be equal        to 0. The value of pps_cr_qp_offset+slice_cr_qp_offset shall be        in the range of −12 to +12, inclusive.        slice_joint_cbcr_qp_offset specifies a difference to be added to        the value of pps_joint_cbcr_qp_offset_value when determining the        value of the Qp′_(CbCr). The value of slice_joint_cbcr_qp_offset        shall be in the range of −12 to +12, inclusive. When        slice_joint_cbcr_qp_offset is not present, it is inferred to be        equal to 0. The value of        pps_joint_cbcr_qp_offset_value+slice_joint_cbcr_qp_offset shall        be in the range of −12 to +12, inclusive.        cu_chroma_qp_offset_enabled_flag equal to 1 specifies that the        cu_chroma_qp_offset_flag may be present in the transform unit        and palette coding syntax. cu_chroma_qp_offset_enabled_flag        equal to 0 specifies that the cu_chroma_qp_offset_flag is not        present in the transform unit or palette coding syntax. When not        present, the value of cu_chroma_qp_offset_enabled_flag is        inferred to be equal to 0.        slice_sao_luma_flag equal to 1 specifies that SAO is enabled for        the luma component in the current slice; slice_sao_luma_flag        equal to 0 specifies that SAO is disabled for the luma component        in the current slice. When slice_sao_luma_flag is not present,        it is inferred to be equal to ph_sao_luma_enabled_flag.        slice_sao_chroma_flag equal to 1 specifies that SAO is enabled        for the chroma component in the current slice;        slice_sao_chroma_flag equal to 0 specifies that SAO is disabled        for the chroma component in the current slice. When        slice_sao_chroma_flag is not present, it is inferred to be equal        to ph_sao_chroma_enabled_flag.        slice_deblocking_filter_override_flag equal to 1 specifies that        deblocking parameters are present in the slice header.        slice_deblocking_filter_override_flag equal to 0 specifies that        deblocking parameters are not present in the slice header. When        not present, the value of slice_deblocking_filter_override_flag        is inferred to be equal to ph_deblocking_filter_override_flag.        slice_deblocking_filter_disabled_flag equal to 1 specifies that        the operation of the deblocking filter is not applied for the        current slice. slice_deblocking_filter_disabled_flag equal to 0        specifies that the operation of the deblocking filter is applied        for the current slice. When        slice_deblocking_filter_disabled_flag is not present, it is        inferred to be equal to ph_deblocking_filter_disabled_flag.        slice_beta_offset_div2 and slice_tc_offset_div2 specify the        deblocking parameter offsets for β and tC (divided by 2) that        are applied to the luma component for the current slice. The        values of slice_beta_offset_div2 and slice_tc_offset_div2 shall        both be in the range of −12 to 12, inclusive. When not present,        the values of slice_beta_offset_div2 and slice_tc_offset_div2        are inferred to be equal to ph_beta_offset_div2 and        ph_tc_offset_div2, respectively.        slice_cb_beta_offset_div2 and slice_cb_tc_offset_div2 specify        the deblocking parameter offsets for β and tC (divided by 2)        that are applied to the Cb component for the current slice. The        values of slice_cb_beta_offset_div2 and slice_cb_tc_offset_div2        shall both be in the range of −12 to 12, inclusive. When not        present, the values of slice_cb_beta_offset_div2 and        slice_cb_tc_offset_div2 are inferred to be equal to        ph_cb_beta_offset_div2 and ph_cb_tc_offset_div2, respectively.        slice_cb_beta_offset_div2 and slice_cb_tc_offset_div2 specify        the deblocking parameter offsets for β and tC (divided by 2)        that are applied to the Cr component for the current slice. The        values of slice_cr_beta_offset_div2 and slice_cr_tc_offset_div2        shall both be in the range of −12 to 12, inclusive. When not        present, the values of slice_cr_beta_offset_div2 and        slice_cr_tc_offset_div2 are inferred to be equal to        ph_cr_beta_offset_div2 and ph_cr_tc_offset_div2, respectively.        slice_ts_residual_coding_disabled_flag equal to 1 specifies that        the residual_coding( ) syntax structure is used to parse the        residual samples of a transform skip block for the current        slice. slice_ts_residual_coding_disabled_flag equal to 0        specifies that the residual_ts_coding( ) syntax structure is        used to parse the residual samples of a transform skip block for        the current slice. When slice_ts_residual_coding_disabled_flag        is not present, it is inferred to be equal to 0.        slice_lmcs_enabled_flag equal to 1 specifies that luma mapping        with chroma scaling is enabled for the current slice.        slice_lmcs_enabled_flag equal to 0 specifies that luma mapping        with chroma scaling is not enabled for the current slice. When        slice_lmcs_enabled_flag is not present, it is inferred to be        equal to 0. slice_scaling_list_present_flag equal to 1 specifies        that the scaling list data used for the current slice is derived        based on the scaling list data contained in the referenced        scaling list APS with aps_params_type equal to SCALING_APS and        adaptationparameter_set_id equal to ph_scaling_list_aps_id.        slice_scaling_list_present_flag equal to 0 specifies that the        scaling list data used for the current picture is the default        scaling list data derived specified in clause 7.4.3.21.        When not present, the value of slice_scaling_list_present_flag        is inferred to be equal to 0.        The variable NumEntryPoints, which specifies the number of entry        points in the current slice, is derived as follows:

NumEntryPoints = 0 for( i = 1; i < NumCtusInCurrSlice; i++ ) {  ctbAddrX= CtbAddrInCurrSlice[ i ] % PicWidthInCtbsY  ctbAddrY =CtbAddrInCurrSlice[ i ] / PicWidthInCtbsY (145)  prevCtbAddrX =CtbAddrInCurrSlice[ i − 1 ] % PicWidthInCtbsY  prevCtbAddrY =CtbAddrInCurrSlice[ i − 1 ] / PicWidthInCtbsY  if( CtbToTileRowBd[ctbAddrY ] != CtbToTileRowBd[  prevCtbAddrY ] | |    CtbToTileColBd[ctbAddrX ] != CtbToTileColBd[    prevCtbAddrX ] | |    ( ctbAddrY !=prevCtbAddrY &&    sps_wpp_entry_point_offsets_present_flag ) )  NumEntryPoints++ }offset_len_minus1 plus 1 specifies the length, in bits, of theentry_point_offset_minus1[i] syntax elements. The value ofoffset_len_minus1 shall be in the range of 0 to 31, inclusive.entry_point_offset_minus1[i] plus 1 specifies the i-th entry pointoffset in bytes, and is represented by offset_len_minus1 plus 1 bits.The slice data that follow the slice header consists of NumEntryPoints+1subsets, with subset index values ranging from 0 to NumEntryPoints,inclusive. The first byte of the slice data is considered byte 0.When present, emulation prevention bytes that appear in the slice dataportion of the coded slice NAL unit are counted as part of the slicedata for purposes of subset identification. Subset 0 consists of bytes 0to entry_point_offset_minus1[0], inclusive, of the coded slice data,subset k, with k in the range of 1 to NumEntryPoints−1, inclusive,consists of bytes firstByte[k] to lastByte[k], inclusive, of the codedslice data with firstByte[k] and lastByte[k] defined as:

firstByte[k]=Σ_(n=1) ^(k)(entry_point_offset_minus1[n−1]+1)  (146)

lastByte[k]=firstByte[k]+entry_point_offset_minus1[k]  (147)

The last subset (with subset index equal to NumEntryPoints) consists ofthe remaining bytes of the coded slice data.When sps_entropy_coding_sync_enabled_flag is equal to 0 and the slicecontains one or more complete tiles, each subset shall consist of allcoded bits of all CTUs in the slice that are within the same tile, andthe number of subsets (i.e., the value of NumEntryPoints+1) shall beequal to the number of tiles in the slice.When sps_entropy_coding_sync_enabled_flag is equal to 0 and the slicecontains a subset of CTU rows from a single tile, the NumEntryPointsshall be 0, and the number of subsets shall be 1. The subset shallconsist of all coded bits of all CTUs in the slice.When sps_entropy_coding_sync_enabled_flag is equal to 1, each subset kwith k in the range of 0 to NumEntryPoints, inclusive, shall consist ofall coded bits of all CTUs in a CTU row within a tile, and the number ofsubsets (i.e., the value of NumEntryPoints+1) shall be equal to thetotal number of tile-specific CTU rows in the slice.slice_header_extension_length specifies the length of the slice headerextension data in bytes, not including the bits used for signallingslice_header_extension_length itself. The value ofslice_header_extension_length shall be in the range of 0 to 256,inclusive. When not present, the value of slice_header_extension_lengthis inferred to be equal to 0.slice_header_extension_data_byte[i] may have any value. Decodersconforming to this version of this Specification shall ignore the valuesof all the slice_header_extension_data_byte[i] syntax elements. Itsvalue does not affect decoder conformance to profiles specified in thisversion of specification.

3.5. Chroma QP Mapping Table

In clause 7.3.2.3 of JVET-Q2001-vC, the SPS includes a structure namedchroma QP table shown as follows:

Descriptor seq_parameter_set_rbsp( ) {  . . . . . .  if( ChromaArrayType!= 0 ) {   sps_joint_cbcr_enabled_flag u(1)   same_qp_table_for_chromau(1)   numQpTables = same_qp_table_for_chroma ? 1 : (sps_joint_cbcr_enabled_flag ? 3 : 2 )   for( i = 0; i < numQpTables; i++) {    qp_table_start_minus26[ i ] se(v)   num_points_in_qp_table_minus1[ i ] ue(v)    for( j = 0; j <=num_points_in_qp_table_minus1[ i ]; j++ ) {     delta_qp_in_val_minus1[i ][ j ] ue(v)     delta_qp_diff_val[ i ][ j ] ue(v)    }   }  }  . . .. . .

They are with the following semantics and QP table derivation:

sps_joint_cbcr_enabled_flag equal to 0 specifies that the joint codingof chroma residuals is disabled. sps_joint_cbcr_enabled_flag equal to 1specifies that the joint coding of chroma residuals is enabled. When notpresent, the value of sps_joint_cbcr_enabled_flag is inferred to beequal to 0.same_qp_table_for_chroma equal to 1 specifies that only one chroma QPmapping table is signalled and this table applies to Cb and Cr residualsand additionally to joint Cb-Cr residuals whensps_joint_cbcr_enabled_flag is equal to 1. same_qp_table_for_chromaequal to 0 specifies that chroma QP mapping tables, two for Cb and Cr,and one additional for joint Cb-Cr when sps_joint_cbcr_enabled_flag isequal to 1, are signalled in the SPS. When same_qp_table_for_chroma isnot present in the bitstream, the value of same_qp_table_for_chroma isinferred to be equal to 1.qp_table_start_minus26[i] plus 26 specifies the starting luma and chromaQP used to describe the i-th chroma QP mapping table. The value ofqp_table_start_minus26[i] shall be in the range of −26−QpBdOffset to 36inclusive. When qp_table_start_minus26[i] is not present in thebitstream, the value of qp_table_start_minus26[i] is inferred to beequal to 0.num_points_in_qp_table_minus1[i] plus 1 specifies the number of pointsused to describe the i-th chroma QP mapping table. The value ofnum_points_in_qp_table_minus1[i] shall be in the range of 0 to63+QpBdOffset, inclusive. When num_points_in_qp_table_minus1[0] is notpresent in the bitstream, the value of num_points_in_qp_table_minus1[0]is inferred to be equal to 0.delta_qp_in_val_minus1[i][j] specifies a delta value used to derive theinput coordinate of the j-th pivot point of the i-th chroma QP mappingtable. When delta_qp_in_val_minus1[0][j] is not present in thebitstream, the value of delta_qp_in_val_minus1[0][j] is inferred to beequal to 0.delta_qp_diff_val[i][j] specifies a delta value used to derive theoutput coordinate of the j-th pivot point of the i-th chroma QP mappingtable.The i-th chroma QP mapping table ChromaQpTable[i] for i=0 . . .numQpTables−1 is derived as follows:

qpInVal[ i ][ 0 ] = qp_table_start_minus26[ i ] + 26 qpOutVal[ i ][ 0 ]= qpInVal[ i ][ 0 ] for( j = 0; j <= num_points_in_qp_table_minus1[ i ];j++ ) {  qpInVal[ i ][ j + 1 ] = qpInVal[ i ][ j ] +delta_qp_in_val_minus1[  i ][ j ] + 1  qpOutVal[ i ][ j + 1 ] =qpOutVal[ i ][ j ] + ( delta_qp_in_val_minus1[ i ][ j ] {circumflex over( )} delta_qp_diff_val[ i ][ j ] ) } ChromaQpTable[ i ][ qpInVal[ i ][ 0] ] = qpOutVal[ i ][ 0 ] for( k = qpInVal[ i ][ 0 ] − 1; k >=−QpBdOffset; k − − )  ChromaQpTable[ i ][ k ] = Clip3( −QpBdOffset, 63, ChromaQpTable[ i ][ k + 1 ] − 1 ) for( j = 0; j <=num_points_in_qp_table_minus1[ i ]; j++ ) {  sh = (delta_qp_in_val_minus1[ i ][j ] + 1 ) >> 1  for( k = qpInVal[ i ][ j ] +1, m = 1; k <= qpInval[ i ][ j + 1 ]; k++,  m++ )   ChromaQpTable[ i ][k ] = ChromaQpTable[ i ][ qpInVal[ i ][ j ] ] +    ( ( qpOutVal[ i ][j +1] − qpOutVal[ i ][j ] ) * m + sh ) / ( delta_qp_in_val_minus1[ i ][j] +1 ) } for( k = qpInVal[ i ][ num_points_in_qp_table_minus1[ i ] + 1 ] +1; k <= 63; k++ )  ChromaQpTable[ i ][ k ] = Clip3( −QpBdOffset, 63, ChromaQpTable[ i ][ k − 1 ] + 1 )When same_qp_table_for_chroma is equal to 1, ChromaQpTable[1][k] andChromaQpTable[2][k] are set equal to ChromaQpTable[0][k] for k in therange of −QpBdOffset to 63, inclusive.It is a requirement of bitstream conformance that the values ofqpInVal[i][j] and qpOutVal[i][j] shall be in the range of −QpBdOffset to63, inclusive for i in the range of 0 to numQpTables−1, inclusive, and jin the range of 0 to num_points_in_qp_table_minus1[i]+1, inclusive.In the above description, QpBdOffset is derived as:bit_depth_minus8 specifies the bit depth of the samples of the luma andchroma arrays, BitDepth, and the value of the luma and chromaquantization parameter range offset, QpBdOffset, as follows:

BitDepth=8+bit_depth_minus8

QpBdOffset=6*bit_depth_minus8

bit_depth_minus8 shall be in the range of 0 to 8, inclusive.

4. Technical Problems Solved by Disclosed Technical Solutions

The existing designs in the latest VVC draft specification for APS,deblocking, subpicture, and QP delta have the following problems:

-   -   1) Currently, the value of the APS syntax element        scaling_list_chroma_present_flag is constrained based on        ChromaArrayType derived from SPS syntax elements        chroma_format_idc and separate_colour_plane_flag, phrased as        follows: scaling_list_chroma_present_flag shall be equal to 0        when ChromaArrayType is equal to 0, and shall be equal to 1 when        ChromaArrayType is not equal to 0.        -   Such constraints in the semantics of the APS syntax element            introduce semantics dependencies of APS on SPS, which should            not occur, because since there is no PPS ID or SPS ID in the            APS syntax, an APS may be applied to pictures (or slices of            pictures) that refer to different SPSs, which may be            associated with different values of ChromaArrayType.            -   a. Additionally, similar APS-SPS semantics dependencies                also exist in the semantics of some ALF/CC-ALF APS                syntax elements, phrased as follows:                alf_chroma_filter_signal_flag,                alf_cc_cb_filter_signal_flag, and                alf_cc_cr_filter_signal_flag shall to be equal to 0 when                ChromaArrayType is equal to 0.            -   b. Currently, when an LMCS APS is signalled, the chroma                residual scaling related syntax elements are always                signalled in the LMCS APS syntax structure, regardless                of whether ChromaArrayType is equal to 0 (i.e., there is                no chroma component in the CLVS). This results in                unnecessary signalling of chroma-related syntax                elements.    -   2) It is asserted that the deblocking control mechanism in the        latest VVC text is pretty complicated, not straightforward, and        not easy to understand, and consequently prone to errors. Here        are some example issues we observed:        -   a. According to the current text, even if the deblocking            filter is disabled in the PPS, it can be enabled in the PH            or SH. For example, if pps_deblocking_filter_disabled_flag            is firstly signalled to be equal to 1, and            deblocking_filter_override_enabled_flag is also signalled to            be equal to 1, it indicates that the deblocking filter is            disabled at PPS and it also allows the deblocking filter            enable/disable control being overridden in the PH or SH.            Then dbf_info_in_ph_flag is signalled subsequently and the            PH syntax element ph_deblocking_filter_disabled_flag might            be signalled to be equal to 0 which ultimately enables the            deblocking filter for slices associated with the PH. In such            case, the deblocking is eventually enabled at PH regardless            that it has been disabled at the higher level (e.g., PPS).            Such design logic is unique in VVC text, and it is quite            different from the design logic of other coding tools (e.g.,            ALF, SAO, LMCS, TMVP, WP, and etc.) as normally when a            coding tool is disabled at a higher layer (e.g., SPS, PPS),            then it is disabled completely at lower layers (e.g., PH,            SH).        -   b. Furthermore, the current definition of            pps_deblocking_filter_disabled_flag is like            “pps_deblocking_filter_disabled_flag equal to 1 specifies            that the operation of deblocking filter is not applied for            slices referring to the PPS in which            slice_deblocking_filter_disabled_flag is not present . . .            ”. However, according to the current syntax table, even            though pps_deblocking_filter_disabled_flag is equal to 1 and            slice_deblocking_filter_disabled_flag is not present, the            operation of deblocking filter would still be applied in            case of ph_deblocking_filter_disabled_flag is present and            signalled to be equal to 0. Therefore, the current            definition of pps_deblocking_filter_disabled_flag is not            correct.        -   c. Moreover, according to the current text, if both the PPS            syntax elements deblocking_filter_override_enabled_flag and            pps_deblocking_filter_disabled_flag are equal to 1, it            specifies that deblocking is disabled in PPS and the control            of deblocking filter is intended to be overridden in the PH            or SH. However, the subsequent PH syntax elements            ph_deblocking_filter_override_flag and            ph_deblocking_filter_disabled_flag might be still signalled            to be equal to 1, which turns out that the resulted            overriding process doesn't change anything (e.g., deblocking            remains disabled in the PH/SH) but just use unnecessary bits            for meaningless signalling.        -   d. In addition, according to the current text, when the SH            syntax element slice_deblocking_filter_override_flag is not            present, it is inferred to be equal to            ph_deblocking_filter_override_flag. However, besides            implicit or explicit signalling in the PPS, the deblocking            parameters can only be signalled either in PH or SH            according to dbf_info_in_ph_flag, but never both. Therefore,            when dbf_info_in_ph_flag is true, the intention is to allow            to signal the overriding deblocking filter parameters in the            PH. In this case, if the PH override flag is true and the SH            override flag is not signalled but inferred to be equal to            the PH override flag, additional deblocking filter            parameters will still be signalled in the SH which is            conflicting with the intention.        -   e. In addition, there is no SPS-level deblocking on/off            control, which may be added and the related syntax elements            in PPS/PH/SH may be updated accordingly.    -   3) Currently, when the PPS syntax element        single_slice_per_subpic_flag is not present, it is inferred to        be equal to 0. single_slice_per_subpic_flag is not present in        two cases: i) no_pic_partition_flag is equal to 1, and ii)        no_pic_partition_flag is equal to 0 and rect_slice_flag is equal        to 0.        -   For case i), no_pic_partition_flag equal to 1 specifies that            no picture partitioning is applied to each picture referring            to the PPS, therefore, there is only one slice in each            picture, and consequently, there is only one subpicture in            each picture and there is only one slice in each subpicture.            Therefore, in this case single_slice_per_subpic_flag should            be inferred to be equal 1.        -   For case ii), since rect_slice_flag is equal to 0, an            inferred value of single_slice_per_subpic_flag is not            needed.    -   4) Currently, luma qp delta in either picture or slice level is        always signalled mandatorily, either in the PH or SH, never        both. Whereas the slice-level chroma QP offset is optionally        signalled in the SH. Such design is somewhat not consistent.        -   a. Additionally, the current semantics of the PPS syntax            element cu_qp_delta_enabled_flag is worded as follows: cu qp            delta enabled flag equal to 1 specifies that the            ph_cu_qp_delta_subdiv_intra_slice and            ph_cu_qp_delta_subdiv_inter_slice syntax elements are            present in PHs referring to the PPS and cu qp delta abs may            be present in the transform unit syntax . . . . However,            cu_qp_delta_abs may be also present in the palette coding            syntax, which should also be specified by            cu_qp_delta_enabled_flag. In other words, the current            semantics of cu_qp_delta_enabled_flag is not clear enough            and a bit confusing.    -   5) The current design of chroma Qp mapping table is not        straightforward to represent the case of chroma Qp equal to luma        Qp.    -   6) Currently, the subpic_treated_as_pic_flag[i] is inferred to        be equal to the value of sps_independent_subpics_flag. However,        the current spec only allows the horizontal wrap-around to be        enabled when subpic_treated_as_pic_flag[i] is equal to 0,        wherein the wrap-around motion compensation is designed for 360        video content. Therefore, when a pictures contains only one        subpicture (especially for the case that a complete 360 video        sequence contains only one subpicture), the inferred value for        subpic_treated_as_pic_flag[i] may be inferred to be equal to 0        or a certain value that allows the wrap-around motion        compensation.    -   7) Currently, the semantics of        pps_deblocking_filter_disabled_flag is not correct and        incomplete. e.g., when pps_deblocking_filter_disabled_flag is        equal to 1, deblocking may be enabled or disabled for slices        referring to this PPS, but those conditions are not mentioned in        the semantics. Similarly for the part of semantics for        pps_deblocking_filter_disabled_flag is equal to 0.        -   a. Furthermore, when the PPS syntax element            pps_deblocking_filter_disabled_flag are equal to 1, and            meanwhile the PH/SH syntax element            ph/slice_deblocking_filter_override_flag is signalled to be            equal to 1, the ph/slice_deblocking_filter_disabled_flag is            still allowed to be explicitly signalled to be equal to 1.            What this combination of values of the flags does is that            deblocking is said at the PPS level to be disabled and            allowed to be overridden at the picture or slice, then it is            indicated at the PH/SH level that it is going to be            overridden, and then a bit is signalled in the same header            (PH/SH) to finally determine that it is actually not            overridden and deblocking remains disabled at the            picture/slice level. This is asserted to have a double            undesirable effects: not only a bit is spent unnecessarily,            it is spent just for causing some confusion. We therefore            propose to further improve the semantics of deblocking            control syntax elements and remove the feature of allowing            indicating overriding and then immediately send the next bit            in the same PH or SH to indicate a change of mind.

5. A Listing of Solutions and Embodiments

To solve the above problems and some other problems not mentioned,methods as summarized below are disclosed. The items listed below shouldbe considered as examples to explain the general concepts and should notbe interpreted in a narrow way. Furthermore, these items can be appliedindividually or combined in any manner.

In the following discussion, an SH may be associated with a PH, i.e.,the SH is associated with a slice, which is in the picture associatedwith the PH. An SH may be associated with a PPS, i.e., the SH isassociated with a slice, which is in the picture associated with thePPS. A PH may be associated with a PPS, i.e., the PH is associated witha picture, which is associated with the PPS.

In the following discussion, a SPS may be associated with a PPS, i.e.,the PPS may refer to the SPS.

In the following discussion, the changed texts are based on the latestVVC text in JVET-Q2001-vE. Most relevant parts that have been added ormodified are

, and some of the deleted parts are marked with double brackets (e.g.,[[a]] denotes the deletion of the character “a”).

-   1. Regarding the constraints on APS syntax elements for solving the    first problem, one or more of the following approaches are    disclosed:    -   a. In one example, constrain the value of        scaling_list_chroma_present_flag according to ChromaArrayType        derived by the PH syntax element.        -   i. For example, whether the value of            scaling_list_chroma_present_flag is constrained or not may            be dependent on whether ph_scaling_list_aps_id is present or            not, e.g., as in the first set of embodiments.            -   1) In one example, it is required that, when                ph_scaling_list_aps_id is present, the value of                scaling_list_chroma_present_flag of the APS NAL unit                having aps_params_type equal to SCALING_APS and                adaptation_parameter_set_id equal to                ph_scaling_list_aps_id shall be equal to                ChromaArrayType==0 ? 0:1.        -   ii. Alternatively, scaling_list_chroma_present_flag is            constrained based on ChromaArrayType derived by the PH            syntax elements, but regardless of the presence of            ph_scaling_list_aps_id, e.g., as in the first set of            embodiments.            -   1) In one example, it is required that, the value of                scaling_list_chroma_present_flag of the APS NAL unit                having aps_params_type equal to SCALING_APS shall be                equal to ChromaArrayType==0 ? 0:1.    -   b. In one example, constrain the value of lmcs_delta_abs_crs        according to ChromaArrayType derived by the PH syntax element.        -   i. For example, whether the value of lmcs_delta_abs_crs is            constrained or not may be dependent on whether            ph_lmcs_aps_id is present or not, e.g., as in the first set            of embodiments.            -   1) For example, it is required that, when ph_lmcs_aps_id                is present, the value of lmcs_delta_abs_crs of the APS                NAL unit having aps_params_type equal to LMCS_APS and                adaptation_parameter_set_id equal to ph_lmcs_aps_id                shall be equal to 0 if ChromaArrayType is equal to 0 and                shall be greater than 0 otherwise.            -   2) Alternatively, it is required that, when                ph_lmcs_aps_id is present, the value of                lmcs_delta_abs_crs of the APS NAL unit having                aps_params_type equal to LMCS_APS and                adaptation_parameter_set_id equal to ph_lmcs_aps_id                shall be equal to 0 if ChromaArrayType is equal to 0.        -   ii. Alternatively, lmcs_delta_abs_crs is constrained based            on ChromaArrayType derived by the PH syntax elements, but            regardless of the presence of ph_lmcs_aps_id, e.g., as in            the first set of embodiments.            -   1) For example, it is required that, the value of                lmcs_delta_abs_crs of the APS NAL unit equal to                ph_lmcs_aps_id shall be equal to 0 if ChromaArrayType is                equal to 0 and shall be greater than 0 otherwise.            -   2) For example, it is required that, the value of                lmcs_delta_abs_crs of the APS NAL unit equal to                ph_lmcs_aps_id shall be equal to 0 if ChromaArrayType is                equal to 0.    -   c. In one example, constrain the value of ALF APS syntax        elements (e.g., alf_chroma_filter_signal_flag,        alf_cc_cb_filter_signal_flag, alf_cc_cr_filter_signal_flag, and        etc.) according to ChromaArrayType derived by the PH syntax        elements and/or the SH syntax elements.        -   i. For example, whether the value of            alf_chroma_filter_signal_flag and/or            alf_cc_cb_filter_signal_flag and/or            alf_cc_cr_filter_signal_flag are constrained or not may be            dependent on whether ph_alf_aps_id_luma[i] or            slice_alf_aps_id_luma[i] is present or not and/or whether            ChromaArrayType is equal to 0 or not, e.g., as in the first            set of embodiments.            -   1) For example, it is required that, when                ph_alf_aps_id_luma[i] is present and ChromaArrayType is                equal to 0, the values of alf_chroma_filter_signal_flag,                alf_cc_cb_filter_signal_flag, and                alf_cc_cr_filter_signal_flag of the APS NAL unit having                aps_params_type equal to ALF_APS and                adaptation_parameter_set_id equal to                ph_alf_aps_id_luma[i] shall all be equal to 0.            -   2) Additionally, it is required that, when                slice_alf_aps_id_luma[i] is present and ChromaArrayType                is equal to 0, the values of                alf_chroma_filter_signal_flag,                alf_cc_cb_filter_signal_flag, and                alf_cc_cr_filter_signal_flag of the APS NAL unit having                aps_params_type equal to ALF_APS and                adaptation_parameter_set_id equal to                slice_alf_aps_id_luma[i] shall all be equal to 0.        -   ii. Alternatively, alf_chroma_filter_signal_flag and/or            alf_cc_cb_filter_signal_flag and/or            alf_cc_cr_filter_signal_flag are constrained based on            ChromaArrayType derived by the PH syntax elements or SH            syntax elements, but regardless of the presence of            ph_alf_aps_id_luma[i] and/or slice_alf_aps_id_luma[i], e.g.,            as in the first set of embodiments.            -   1) For example, it is required that, when                ChromaArrayType is equal to 0, the values of                alf_chroma_filter_signal_flag,                alf_cc_cb_filter_signal_flag, and                alf_cc_cr_filter_signal_flag of the APS NAL unit having                aps_params_type equal to ALF_APS shall all be equal to                0.            -   2) Additionally, it is required that, when                ChromaArrayType is equal to 0, the values of                alf_chroma_filter_signal_flag,                alf_cc_cb_filter_signal_flag, and                alf_cc_cr_filter_signal_flag of the APS NAL unit having                aps_params_type equal to ALF_APS shall all be equal to                0.        -   iii. Alternatively, alf_chroma_filter_signal_flag and/or            alf_cc_cb_filter_signal_flag and/or            alf_cc_cr_filter_signal_flag are constrained based on            ChromaArrayType derived by the chroma APS ID related PH or            SH syntax elements, e.g., as in the first set of            embodiments.            -   1) For example, alf_chroma_filter_signal_flag is                constrained according to ChromaArrayType derived by the                PH syntax element ph_alf_aps_id_chroma and/or the SH                syntax element slice_alf_aps_id_chroma.            -   2) For example, alf_cc_cb_filter_signal_flag is                constrained according to ChromaArrayType derived by the                PH syntax element ph_cc_alf_cb_aps_id and/or the SH                syntax element slice_cc_alf_cb_aps_id.            -   3) For example, alf_cc_cr_filter_signal_flag is                constrained according to ChromaArrayType derived by the                PH syntax element ph_cr_alf_cb_aps_id and/or the SH                syntax element slice_cr_alf_cb_aps_id.    -   d. In one example, the semantics of APS syntax elements in the        ALF and/or SCALING LIST and/or LMCS data syntax structure may be        not dependent on whether it is 4:0:0 video coding and/or        separate color plane coding.        -   i. For example, the semantics of APS syntax elements in the            ALF data syntax structure (e.g.,            alf_chroma_filter_signal_flag, alf_cc_cb_filter_signal_flag,            alf_cc_cr_filter_signal_flag, and etc.) may be not dependent            on variables/syntaxes derived by SPS/PH/SH syntax elements            (e.g., ChromaArrayType), e.g., as in the first set of            embodiments.        -   ii. Additionally, alternatively, the semantics of APS syntax            elements in the SCALING LIST data syntax structure (e.g.,            scaling_list_chroma_present_flag, and etc.) may be not            dependent on variables/syntaxes derived by SPS/PH/SH syntax            elements (e.g., ChromaArrayType), e.g., as in the first set            of embodiments.    -   e. Additionally, whether the temporalId of the ALF/SCALING/LMCS        APS NAL unit is constrained or not may be dependent on whether        the corresponding APS ID is present or not, e.g., as in the        first set of embodiments.        -   i. For example, whether the temporalId of the ALF APS NAL            unit is constrained or not may be dependent on whether            ph_alf_aps_id_luma[i] and/or ph_alf_aps_id_chroma and/or            ph_cc_alf_cb_aps_id and/or ph_cc_alf_cr_aps_id is present or            not.        -   ii. For example, whether the temporalId of the LMCS APS NAL            unit is constrained or not may be dependent on whether            ph_lmcs_aps_id is present or not.        -   iii. For example, whether the temporalId of the SCALING APS            NAL unit is constrained or not may be dependent on whether            ph_scaling_list_aps_id is present or not.    -   f. Additionally, whether the values of        alf_luma_filter_signal_flag, alf_chroma_filter_signal_flag        and/or alf_cc_cb_filter_signal_flag and/or        alf_cc_cr_filter_signal_flag shall be equal to 1 may be        dependent on whether the corresponding APS ID is present or not,        e.g., as in the first set of embodiments.        -   i. For example, whether alf_luma_filter_signal_flag shall be            equal to 1 or not may be dependent on whether            ph_alf_aps_id_luma[i] and/or slice_alf_aps_id_luma[i] is            present or not.        -   ii. For example, whether alf_chroma_filter_signal_flag shall            be equal to 1 or not may be dependent on whether            ph_alf_aps_id_chroma and/or slice_alf_aps_id_chroma is            present or not.        -   iii. For example, whether alf_cc_cb_filter_signal_flag shall            be equal to 1 or not may be dependent on whether            ph_cc_alf_cb_aps_id and/or slice_cc_alf_cb_aps_id is present            or not.        -   iv. For example, whether alf_cc_cr_filter_signal_flag shall            be equal to 1 or not may be dependent on whether            ph_cc_alf_cr_aps_id and/or slice_cc_alf_cr_aps_id is present            or not.    -   g. Additionally, alternatively, whether the chroma ALF APS ID        syntax elements in the SH (e.g., slice_alf_aps_id_chroma,        slice_cc_alf_cb_aps_id, slice_cr_alf_cb_aps_id, and etc.) in        inferred or not may be dependent on the value of        ChromaArrayType, e.g., as in the first set of embodiments.        -   i. For example, when ChromaArrayType is not equal to 0, the            value of the chroma ALF APS ID syntax elements in the SH            (e.g., slice_alf_aps_id_chroma, slice_cc_alf_cb_aps_id,            slice_cr_alf_cb_aps_id, and etc.) may be inferred.    -   h. In one example, the constraint of APS syntax elements based        on ChromaArrayType may be derived by the PH or SH syntax        elements.        -   i. Alternatively, the constraints of one or multiple syntax            elements in an APS, such as indications of chroma            information presence (e.g., whether chroma filters are            signalled, chroma scaling list are signalled, LMCS residual            scaling factor is equal to 0), may be defined in the            semantics of PH and/or SH syntax elements.            -   a) Alternatively, furthermore, the PH and/or SH syntax                elements may refer to an APS.            -   b) Alternatively, furthermore, the constraints of a same                syntax element in different APS types may be different,                i.e., using one-way (e.g., when certain condition is                true, a constrain is applied) or two-way constraints                (e.g., if certain condition is true, a first constrain                is applied; otherwise, a second constrain is applied).        -   ii. In one example, the APS in which syntax elements are            constrained is determined by an index (such as            ph_num_alf_aps_ids_luma, ph_alf_aps_id_chroma,            ph_lmcs_aps_id and ph_scaling_list_aps_id) signaled in PH or            SH.        -   iii. In one example, ChromaArrayType may be derived by            information (such as chroma_format_idc and            separate_colour_plane_flag) signaled in a SPS, which is            determined by an index (such as pps_seq_parameter_set_id)            signaled in a PPS, which is further determined by an index            (such as ph_pic_parameter_set_id) signaled in the PH or SH.        -   iv. In one example, the constraints should be checked after            parsing the APS and the PH or SH.        -   v. In one example, a syntax element (e.g., named            aps_chroma_present_flag) may be signalled in the APS syntax            structure (e.g., adaptation_parameter_set_rbsp( ))            specifying whether the chroma-related APS syntax elements            would be signalled or not.            -   a) In one example, the syntax element may be defined as                that in the sixth embodiment.            -   b) Alternatively, the syntax element (e.g., named                aps_chroma_present_flag) may be used to control the                presence of other syntax elements in the APS and/or how                to signal the other syntax elements and/or how to derive                the inferred values of the other syntax elements.            -   c) For example, aps_chroma_present_flag equal to a                certain value (such as 1) specifies that chroma-related                APS syntax elements may be present in the                LMCS/SCALING/ALF APS data.            -   d) For example, aps_chroma_present_flag equal to a                certain value (such as 0) specifies that chroma-related                APS syntax element is not present in the                LMCS/SCALING/ALF APS data.            -   e) For example, aps_chroma_params_present_flag equal to                1 specifies that the APS NAL unit may include chroma                information. aps_chroma_params_present_flag equal to 0                specifies that the APS NAL unit does not include chroma                information.            -   f) For example, when aps_chroma_present_flag is equal to                a certain value (such as 0 or 1), the chroma-related APS                syntax elements in the ALF APS syntax structure (e.g.,                alf_chroma_filter_signal_flag,                alf_cc_cb_filter_signal_flag, and                alf_cc_cr_filter_signal_flag in the alf_data( )) may be                not signalled.            -   g) For example, when aps_chroma_present_flag is equal to                a certain value (such as 0 or 1), the chroma-related APS                syntax elements in the LMCS APS syntax structure (e.g.,                lmcs_delta_abs_crs and/or lmcs_delta_sign_crs_flag in                the lmcs_data( )) may be not signalled.            -   h) For example, when aps_chroma_present_flag is equal to                a certain value (such as 0 or 1), the chroma-related APS                syntax elements in the SCALING APS syntax structure                (e.g., scaling_list_copy_mode_flag[id],                scaling_list_pred_id_delta[id],                scaling_list_dc_coef[id−14],                scaling_list_delta_coef[id][i] in the scaling_data( ))                may be not signalled, wherein id is a number.                -   a. For example, id is equal to some values in the                    range of 0 to X, inclusive (such as X=27).                -   b. For example, id is not equal to X (such as X=27).                -   c. For example, id % M is not equal to N (such as                    M=3, N=2).            -   i) For example, when a chroma-related APS syntax element                is not present, it is inferred to be equal to a certain                value (such as 0 or 1).        -   vi. In one example, when the chroma-related APS syntax            elements are allowed to be present (e.g.,            aps_chroma_present_flag is equal to 1), it is required that            at least one of alf_chroma_filter_signal_flag,            alf_cc_cb_filter_signal_flag, and            alf_cc_cr_filter_signal_flag shall be equal to 1.        -   vii. Alternatively, when the chroma-related APS syntax            elements are allowed to be present (e.g.,            aps_chroma_present_flag is equal to 1), the signalling of            the syntax element X may be dependent on the values of the            syntax elements in the set of Y.            -   a) For example, X is alf_chroma_filter_signal_flag, and                Y includes alf_cc_cb_filter_signal_flag and                alf_cc_cr_filter_signal_flag.            -   b) For example, X is alf_cc_cb_filter_signal_flag, and Y                includes alf_chroma_filter_signal_flag and                alf_cc_cr_filter_signal_flag.            -   c) For example, X is alf_cc_cr_filter_signal_flag, and Y                includes alf_chroma_filter_signal_flag and                alf_cc_cb_filter_signal_flag.            -   d) For example, when the values of the elements in Y are                equal to 0, then the signalling of A is skipped.            -   e) For example, the value of X is inferred to be equal                to a certain value (such as 0 or 1) when not present.            -   f) For example, the value of X is inferred to be equal                to whether the chroma-related APS syntax element are                allowed to be present (e.g., set to the value of                aps_chroma_present_flag).        -   viii. Additionally, the syntax element            aps_chroma_present_flag may be constrained by            ChromaArrayType.            -   a) For example, aps_chroma_present_flag shall be equal                to 0 if ChromaArrayType is equal to 0.            -   b) For example, aps_chroma_present_flag shall be equal                to 1 if ChromaArrayType is larger than 0.        -   ix. Additionally, the constraint based on ChromaArrayType            may be derived by the PH or SH syntax elements.            -   a) In one example, the constraint based on                ChromaArrayType may be defined as that in the sixth                embodiment.            -   b) For example, the syntax element                aps_chroma_present_flag may be constrained depending on                ChromaArrayType and the type of the APSs (such as ALF                APS, SCALING APS or LMCS APS).            -   c) Alternatively, the value of ChromaArrayType may be                constrained depending on the syntax element                aps_chroma_present_flag and/or the type of the APS.            -   d) In one example, it is required that, the value of                aps_chroma_present_flag of the APS NAL unit having                aps_params_type equal to ALF_APS and                adaptation_parameter_set_id equal to                ph/slice_alf_aps_id_luma[i] shall be equal to 0 when                chromaArrayType is equal to 0.                -   a. Additionally, alternatively, it is required that,                    the value of aps_chroma_present_flag of the APS NAL                    unit having aps_params_type equal to ALF_APS and                    adaptation_parameter_set_id equal to                    ph/slice_alf_aps_id_chroma (and/or                    ph_cc_alf_cb_aps_id and/or ph_cc_alf_cr_aps_id)                    shall be equal to 1 when chromaArrayType is greater                    than 0.            -   e) In one example, it is required that, the value of                aps_chroma_present_flag of the APS NAL unit having                aps_params_type equal to SCALING_APS and                adaptation_parameter_set_id equal to                ph_scaling_list_aps_id shall be equal to 0 when                chromaArrayType is equal to 0.                -   a. Additionally, alternatively, it is required that,                    the value of aps_chroma_present_flag of the APS NAL                    unit having aps_params_type equal to SCALING_APS and                    adaptation_parameter_set_id equal to                    ph_scaling_list_aps_id shall be equal to 1 when                    chromaArrayType is greater than 0.            -   f) In one example, it is required that, the value of                aps_chroma_present_flag of the APS NAL unit having                aps_params_type equal to LMCS_APS and                adaptation_parameter_set_id equal to ph_lmcs_aps_id                shall be equal to 0 when chromaArrayType is equal to 0.                -   a. Additionally, alternatively, it is required that,                    the value of aps_chroma_present_flag of the APS NAL                    unit having aps_params_type equal to LMCS_APS and                    adaptation_parameter_set_id equal to ph_lmcs_aps_id                    shall be equal to 1 when chromaArrayType is greater                    than 0.        -   x. Additionally, the constraint based on ChromaArrayType may            be derived by the PH syntax elements or SH syntax elements,            but regardless of the presence of the APS ID in the PH/SH.            -   a) In one example, it is required that, the value of                aps_chroma_present_flag of the APS NAL unit having                aps_params_type equal to SCALING_APS and/or ALF_APS                and/or LMCS APS shall be equal to 0 when chromaArrayType                is equal to 0.            -   b) Additionally, alternatively, it is required that, the                value of aps_chroma_present_flag of the APS NAL unit                having aps_params_type equal to SCALING_APS APS and/or                ALF_APS and/or LMCS APS shall be equal to 1 when                chromaArrayType is greater than 0.-   2. Regarding the signalling of deblocking control for solving the    second problem, one or more of the following approaches are    disclosed, e.g., as in the second set of embodiments:    -   a. In one example, an N-bit (such as N=2) deblocking mode        indicator (e.g., named deblocking_filter_mode_idc) is signalled.        -   i. In one example, the syntax element            deblocking_filter_mode_idc is u(2) coded.            -   a) Alternatively, the parsing process of                deblocking_filter_mode_idc is unsigned integer with N                (such as N=2) bits.        -   ii. In one example, the syntax element            deblocking_filter_mode_idc is signalled in the PPS.        -   iii. In one example, the syntax element            deblocking_filter_mode_idc is used to specify the following            four modes: a) deblocking fully disabled and not used for            all slices; b) deblocking used for all slices using 0-valued            β and tC offsets; c) deblocking used for all slices using β            and tC offsets explicitly signalled in the PPS; and d)            deblocking further controlled at either picture or slice            level.    -   b. A syntax flag ph/slice_deblocking_filter_used_flag is        signalled either in the PH or SH, specifying whether deblocking        is used for the current picture/slice.    -   c. A syntax flag ph/slice_deblocking_parameters_override_flag is        signalled either in the PH or SH, specifying whether the β and        tC offsets are overridden by the values signalled in the PH/SH.        -   i. Additionally, infer the value of            slice_deblocking_parameters_override_flag to be equal to 0            when not present.    -   d. In one example, the syntax elements specifying the deblocking        control (e.g., enable flag, disable flag, control flag,        deblocking mode indicator, deblocking filter beta/tc parameters,        and etc.) may be signalled in the SPS.        -   i. In one example, one or more syntax elements may be            signalled in the SPS specifying whether the deblocking is            enabled or not in the video unit (e.g., CLVS).        -   ii. Additionally, when the deblocking is disabled in the            SPS, it is required that the syntax element in the PPS/PH/SH            regarding the deblocking on/off control at PPS/PH/SH level            shall be equal to a certain value that specifying the            deblocking is fully disabled and not used for all slices.        -   iii. In one example, the deblocking filter control present            flag may be signalled in the SPS.        -   iv. For example, an N-bit (such as N=2) deblocking mode            indicator (e.g., named deblocking_filter_mode_idc) may be            signalled in the SPS.        -   v. For example, beta/tc deblocking parameters may be            signalled in the SPS.        -   vi. For example, whether the deblocking is enabled with            0-valued beta/tc deblocking parameters may be dependent on            the SPS syntax element.        -   vii. For example, the deblocking may be applied at the            SPS/PPS/PH/SH level and use the beta/tc deblocking            parameters signalled in the SPS.        -   viii. For example, the deblocking may be applied at the            SPS/PPS/PH/SH level and use the 0-valued deblocking            parameters signalled in the SPS.-   3. Regarding the inference of the PPS syntax element    single_slice_per_subpic_flag for solving the third problem, one or    more of the following approaches are disclosed:    -   a. In one example, infer single_slice_per_subpic_flag to be        equal to 1 when no_pic_partition_flag is equal to 1, e.g., the        semantics of single_slice_per_subpic_flag is changed as follows:        -   single_slice_per_subpic_flag equal to 1 specifies that each            subpicture consists of one and only one rectangular slice.            single_slice_per_subpic_flag equal to 0 specifies that each            subpicture may consist of one or more rectangular slices.            When            [[not present]], the value of single_sliceper_subpic_flag is            inferred to be equal to [[0]]-   4. Regarding the picture or slice QP delta signalling for solving    the fourth problem, one or more of the following approaches are    disclosed:    -   a. In one example, picture or slice level chroma QP offset are        always signalled, either in the PH or SH.        -   i. For example, if there is chroma component in the video            content (e.g., ChromaArrayType is not equal to 0), picture            or slice level chroma QP offset may be always signalled,            without conditioned on the present flag signalled in the PPS            (e.g., pps_slice_chroma_qp_offsets_present_flag).        -   ii. Alternatively, if there is chroma component in the video            content (e.g., ChromaArrayType is not equal to 0),            slice_cb_qp_offset and slice_cr_qp_offset syntax elements            may be always present in the associated slice headers,            regardless the PPS present flag (e.g.,            pps_slice_chroma_qp_offsets_present_flag).        -   iii. Additionally, the present flag (e.g.,            pps_slice_chroma_qp_offsets_present_flag) specifying the            presence of slice_cb_qp_offset and slice_cr_qp_offset syntax            elements, may be not signalled.    -   b. In one example, pps_cu_qp_delta_enabled_flag may be used to        specify the presence of cu_qp_delta_abs and        cu_qp_delta_sign_flag in both the transform unit syntax and the        palette coding syntax, and the semantics of        pps_cu_qp_delta_enabled_flag are changed as follows:        -   equal to 1 specifies that the            ph_cu_qp_delta_subdiv_intra_slice and            ph_cu_qp_delta_subdiv_inter_slice syntax elements are            present in PHs referring to the PPS, and            cu_qp_delta_abs            may be present in the transform unit syntax            pps_cu_qp_delta_enabled_flag equal to 0 specifies that the            ph_cu_qp_delta_subdiv_intra_slice and            ph_cu_qp_delta_subdiv_inter_slice syntax elements are not            present in PHs referring to the PPS, and            cu_qp_delta_abs            [[is]] not present in the transform unit syntax    -   c. In one example, the luma QP delta may be signalled in both        the PH and the SH.        -   i. For example, luma QP delta present flag may be signalled            in the PPS and/or PH, and/or the SH.        -   ii. For example, whether the luma QP delta is signalled in            PH/SH is dependent on the present flags in the PPS and/or            PH/SH.        -   iii. For example, the values of the PH luma QP delta and the            SH luma QP delta may be additive and used for calculating            the luma quantization parameter such as SliceQp_(Y).    -   d. In one example, the chroma QP offsets may be signalled in        both the PH and the SH.        -   i. For example, chroma QP offsets present flag may be            signalled in the PPS and/or PH, and/or the SH.        -   ii. For example, whether the chroma QP offsets are signalled            in PH/SH is dependent on the present flags in the PPS and/or            PH/SH.        -   iii. For example, the values of the PH chroma QP offsets and            the SH chroma QP offsets may be additive and used for            deriving the chroma quantization parameter for the Cb and Cr            components.-   5. Regarding the chroma Qp mapping tables, one or more of the    following approaches are disclosed:    -   a. In one example, in the derivation process of the chroma QP        table, the XOR operator should be performed between        (delta_qp_in_val_minus1[i][j]+1) and delta_qp_diff_val[i][j],        e.g. as in the third set of embodiment.    -   b. It is proposed to have a flag in        sps_multiple_sets_of_chroma_qp_table_present_flag in SPS.        -   i. When sps_multiple_sets_of_chroma_qp_table_present_flag is            equal to 0, only one set of chroma Qp mapping table is            allowed to be signalled.        -   ii. When sps_multiple_sets_of_chroma_qp_table_present_flag            is equal to 1, more than one set of chroma Qp mapping table            are allowed to be signalled.    -   c. More than one set of chroma Qp mapping tables may be        disallowed to be signalled for a sequence without B/P slices.-   6. Regarding the sps_independent_subpics_flag and    subpic_treated_as_pic_flag[i] for solving the sixth problem, one or    more of the following approaches are disclosed:    -   a. In one example, the presence of sps_independent_subpics_flag        is dependent on whether the number of subpictures is greater        than 1.        -   i. For example, only when the number of subpictures is            greater than 1 (e.g., if (sps_num_subpics_minus1>0)),            sps_independent_subpics_flag is signalled.        -   ii. For example, when the number of subpictures is equal to            1 (e.g., if (sps_num_subpics_minus1==0)), then the            signalling of sps_independent_subpics_flag is skipped.    -   b. Additionally, when sps_independent_subpics_flag is not        present, it is inferred to be equal to a certain value (such as        0 or 1).    -   c. In one example, when subpic_treated_as_pic_flag[i] is not        present, it is inferred to be equal to a certain value (such as        0 or 1).    -   d. In one example, when subpic_treated_as_pic_flag[i] is not        present, it is inferred to be equal to a certain value wherein        the wrap-around motion compensation is enabled (or may be used).        -   i. Additionally, when subpic_treated_as_pic_flag[i] is not            present, it is inferred to be equal to a certain value            wherein the horizontal wrap-around motion compensation is            enabled (or may be used).    -   e. In one example, the inferred value of        subpic_treated_as_pic_flag[i] may be dependent on whether a        picture only consists of one subpicture; and/or whether the        subpicture has the same width as the picture.        -   i. In one example, if the subpicture has the same width as            the picture, subpic_treated_as_pic_flag[i] may be inferred            to X (e.g., X=0).    -   f. In one example, when sps_independent_subpics_flag is not        present, what value that sps_independent_subpics_flag is        inferred to may be dependent on other syntax element(s) or        variable(s).        -   i. For example, the inferred value may depend on whether the            subpicture information is present or not (e.g.,            subpic_info_present_flag is equal to 0 or 1).        -   ii. For example, when subpic_info_present_flag is equal to 0            and sps_independent_subpics_flag is not present, it is            inferred to be equal to a certain value (such as 0 or 1).        -   iii. For example, when subpic_info_present_flag is equal to            1 and sps_independent_subpics_flag is not present, it is            inferred to be equal to a certain value (such as 0 or 1).    -   g. In one example, when subpic_treated_as_pic_flag[i] is not        present, what value that subpic_treated_as_pic_flag[i] is        inferred to may be dependent on the presence of subpicture        information (e.g., subpic_info_present_flag) and/or the number        of subpictures in the CLVS (e.g., sps_num_subpics_minus1) and/or        sps_independent_subpics_flag.        -   i. In one example, when subpic_info_present_flag is equal to            0, and subpic_treated_as_pic_flag[i] is not present, the            value of subpic_treated_as_pic_flag[i] is inferred to be            equal to a certain value (such as 0).        -   ii. In one example, when subpic_info_present_flag is equal            to 1, and subpic_treated_as_pic_flag[i] is not present, the            value of subpic_treated_as_pic_flag[i] is inferred to be            equal to a certain value (such as 1).        -   iii. In one example, when subpic_info_present_flag is equal            to 1, and sps_num_subpics_minus1 is equal to 0, and            subpic_treated_as_pic_flag[i] is not present, the value of            subpic_treated_as_pic_flag[i] is inferred to be equal to a            certain value (such as 0 or 1).        -   iv. In one example, when subpic_info_present_flag is equal            to 1, sps_num_subpics_minus1 is greater than 0,            sps_independent_subpics_flag is equal to 1, and            subpic_treated_as_pic_flag[i] is not present, the value of            subpic_treated_as_pic_flag[i] is inferred to be equal to a            certain value (such as 0 or 1).-   7. How to do padding or clipping on a boundary during the    inter-prediction process may depend on a combined checking of the    type of boundary, the indication of wrap around padding or clipping    (e.g. pps_ref_wraparound_enabled_flag,    sps_ref_wraparound_enabled_flag, and etc.) and the indication of    treating subpicture boundary as picture boundary (e.g.    subpic_treated_as_pic_flag[i]).    -   a. For example, if a boundary is a picture boundary, the        indication of wrap around padding is true, wrap around padding        (or wrap around clipping) may be applied, without considering        the indication of treating subpicture boundary as picture        boundary.        -   i. In one example, the boundary must be a vertical boundary.    -   b. For example, if both two vertical boundaries are picture        boundaries, the indication of wrap around padding is true, wrap        around padding (or wrap around clipping) may be applied, without        considering the indication of treating subpicture boundary as        picture boundary.    -   c. In one example, the above wrap around padding (or wrap around        clipping) may indicate horizontal wrap-around padding/clipping.-   8. In one example, different indications for wrap around padding or    clipping may be signaled for different subpictures.-   9. In one example, different offsets for wrap around padding or    clipping may be signaled for different subpictures.-   10. In the PH/SH, a variable X is used to indicate whether B slice    is allowed/used in a picture/slice, and the variable may be derived    using one of the following ways: a) (rpl_info_in_ph_flag &&    num_ref_entries[0][RplsIdx[0]]>0 &&    num_ref_entries[1][RplsIdx[1]]>0); b) (rpl_info_in_ph_flag &&    num_ref_entries[1][RplsIdx[1]]>0); c) (rpl_info_in_ph_flag &&    num_ref_entries[1][RplsIdx[1]]>1); d) (rpl_info_in_ph_flag &&    num_ref_entries[1][RplsIdx[1]]>0); e) based on NumRefIdxActive    (e.g., NumRefIdxActive for list 1 greater than K (e.g., K=0)) in the    VVC text; f) based on number of allowed reference pictures for list    1.    -   1) Alternatively, furthermore, signalling and/or semantics        and/or inference of one or multiple syntax elements signalled in        PH may be modified according to the variable.        -   i. In one example, the one or multiple syntax elements are            those for enabling a coding tool which requires more than            one prediction signal, such as bi-prediction or mixed intra            and inter coding, or prediction with linear/non-linear            weighting from multiple prediction blocks.        -   ii. In one example, the one or multiple syntax elements may            include, but not limited to:            -   a) ph_collocated_from_I0_flag            -   b) mvd_l1_zero flag            -   c) ph_disable_bdof_flag            -   d) ph_disable_dmvr_flag            -   e) num_l1_weights        -   iii. In one example, only when the variable indicates that            the picture may contain one or more B slices, the one or            multiple syntax elements may be signalled. Otherwise, the            signalling is skipped, and the values of the syntax element            are inferred.            -   a) Alternatively, furthermore, whether to signal the one                or more syntax elements may depend on the first syntax                elements in bullet 1.1) and 2.1), such as (X being true                or 1).            -   b) ph_disable_bdof_flag may be signalled only when                (sps_bdof_pic_present_flag                ) is true.            -   c) ph_disable_dmvr_flag may be signalled only when                (sps_dmvr_pic_present_flag                ) is true.        -   iv. In one example, when X is equal to 0 (or false),            mvd_l1_zero_flag is not signalled, and its values is            inferred to be 1.        -   v. In one example, the inference of the one or multiple            syntax elements are dependent on the value of the first            syntax element.            -   a) In one example, for the ph_disable_bdof_flag, the                following applies:                -   If sps_bdof_enabled_flag is equal to 1                    , the value of ph_disable_bdof_flag is inferred to                    be equal to 0.                -   Otherwise (sps_bdof_enabled_flag is equal to 0                    , the value of ph_disable_bdof_flag is inferred to                    be equal to 1.            -   b) In one example, for the ph_disable_dmvr_flag, the                following applies:                -   If sps_dmvr_enabled_flag is equal to 1                    , the value of ph_disable_dmvr_flag is inferred to                    be equal to 0.                -   Otherwise (sps_dmvr_enabled_flag is equal to 0                    ), the value of ph_disable_dmvr_flag is inferred to                    be equal to 1.            -   c) In one example, when ph_temporal_mvp_enabled_flag and                rpl_info_in_ph_flag are both equal to 1 and X is equal                to 0 (or false), the value of ph_collocated_from_l0_flag                is inferred to be equal to 1.            -   d) In one example, when X is equal to 0 (or false),                num_l1_weights is not signalled and its value is                inferred to be 0, and, consequently, weighted prediction                parameters for reference picture list 1 are not                signalled in the PH or SHs of the picture.-   11. It is proposed that the signaling of indication of whether to    partition a picture into tiles/slices/subpictures (such as    no_pic_partition_flag in PPS) maybe conditioned on the number of    CTBs in a picture.    -   1) In one example, no_pic_partition_flag is not signaled if the        number of CTUs in a picture is equal to 1 (or smaller than 2).    -   2) Alternatively, it is constrained that no_pic_partition_flag        shall be equal to 0 if the number of CTUs in a picture is equal        to 1 (or smaller than 2).-   12. Regarding improving the syntax and semantics of deblocking for    solving the seventh problem, one or more of the following approaches    are disclosed, e.g., as in the fourth embodiment:    -   a. Whether the operation of deblocking filter is disabled (or        enabled) for slices referring to the PPS is dependent on both        the deblocking syntax signalled in the PPS (e.g.,        pps_deblocking_filter_disabled_flag) and the deblocking syntax        elements signalled at the picture or slice level.        -   i. In one example, pps_deblocking_filter_disabled_flag equal            to 1 specifies that the operation of deblocking filter is            disabled for slices referring to the PPS unless indicated            otherwise at the picture or slice level.        -   ii. In one example, pps_deblocking_filter_disabled_flag            equal to 0 specifies that the operation of deblocking filter            is enabled for slices referring to the PPS unless indicated            otherwise at the picture or slice level.    -   b. Infer slice_deblocking_filter_override_flag to be equal to 0        when not present.    -   c. Skip the signalling of deblocking on/off control flag in the        PH/SH when deblocking filter is disabled in the PPS and going to        be overridden in the PH/SH.        -   i. In one example, whether to signal deblocking on/off            control flag in the PH (e.g.,            ph_deblocking_filter_disabled_flag) may be dependent on            whether the deblocking is disabled in the PPS (e.g., whether            the value of pps_deblocking_filter_disabled_flag is equal to            1 or not) and/or the override flag in the PH (e.g.,            ph_deblocking_filter_override_flag is equal to 1 or not).            -   a) For example, when pps_deblocking_filter_disabled_flag                and ph_deblocking_filter_override_flag are equal to 1,                the signalling of ph_deblocking_filter_disabled_flag may                be skipped.            -   b) Alternatively, when                deblocking_filter_override_enabled_flag and                pps_deblocking_filter_disabled_flag and                ph_deblocking_filter_override_flag are equal to 1, the                signalling of ph_deblocking_filter_disabled_flag may be                skipped.        -   ii. Additionally, when ph_deblocking_filter_disabled_flag is            not present, it may be inferred as follows:            -   a) If deblocking_filter_override_enabled_flag,                pps_deblocking_filter_disabled_flag and                ph_deblocking_filter_override_flag are all equal to 1,                the value of ph_deblocking_filter_disabled_flag is                inferred to be equal to 0.            -   b) Otherwise, the value of                ph_deblocking_filter_disabled_flag is inferred to be                equal to pps_deblocking_filter_disabled_flag.        -   iii. Additionally, alternatively, when            ph_deblocking_filter_disabled_flag is not present, it may be            inferred as follows:            -   a) If pps_deblocking_filter_disabled_flag and                ph_deblocking_filter_override_flag are all equal to 1,                the value of ph_deblocking_filter_disabled_flag is                inferred to be equal to 0.            -   b) Otherwise, the value of                ph_deblocking_filter_disabled_flag is inferred to be                equal to pps_deblocking_filter_disabled_flag.        -   iv. In one example, whether to signal deblocking on/off            control flag in the SH (e.g.,            slice_deblocking_filter_disabled_flag) may be dependent on            whether the deblocking is disabled in the PPS (e.g., whether            the value of pps_deblocking_filter_disabled_flag is equal to            1 or not) and/or the override flag in the SH (e.g.,            slice_deblocking_filter_override_flag is equal to 1 or not).            -   a) In one example, when                deblocking_filter_override_enabled_flag and                pps_deblocking_filter_disabled_flag and                slice_deblocking_filter_override_flag are equal to 1,                the signalling of slice_deblocking_filter_disabled_flag                may be skipped.            -   b) Alternatively, when                pps_deblocking_filter_disabled_flag and                slice_deblocking_filter_override_flag are equal to 1,                the signalling of slice_deblocking_filter_disabled_flag                may be skipped.        -   v. Additionally, when slice_deblocking_filter_disabled_flag            is not present, it may be inferred as follows:            -   a) If deblocking_filter_override_enabled_flag,                pps_deblocking_filter_disabled_flag and                slice_deblocking_filter_override_flag are all equal to                1, the value of slice_deblocking_filter_disabled_flag is                inferred to be equal to 0.            -   b) Otherwise, the value of                slice_deblocking_filter_disabled_flag is inferred to be                equal to pps_deblocking_filter_disabled_flag.        -   vi. Additionally, alternatively, when            slice_deblocking_filter_disabled_flag is not present, it may            be inferred as follows:            -   a) If pps_deblocking_filter_disabled_flag and                slice_deblocking_filter_override_flag are all equal to                1, the value of slice_deblocking_filter_disabled_flag is                inferred to be equal to 0.            -   b) Otherwise, the value of                slice_deblocking_filter_disabled_flag is inferred to be                equal to pps_deblocking_filter_disabled_flag.-   13. It is proposed that cu_skip_flag may be skipped when    sps_ibc_enabled_flag is equal to 1 and block size is no smaller than    64×64.    -   a. An example is shown in the fifth embodiment.-   14. A first syntax element (SE) may be added in the ALF APS to    indicate whether chroma filtering information (e.g., chroma ALF,    CC-ALF) are present, and signalling of other syntax elements may be    based on the value of the first SE.    -   a. In one example, when the first SE (e.g.,        aps_chroma_present_flag in embodiment #6) indicates chroma        filtering information are not present, the signalling of        indication of luma filter information (e.g.,        alf_luma_filter_signal_flag) is skipped.        -   i. Alternatively, furthermore, the indication of luma filter            information (e.g., alf_luma_filter_signal_flag) is inferred            to be true.    -   b. In one example, when the first SE (e.g.,        aps_chroma_present_flag in embodiment #6) indicates chroma        filtering information are present, a constraint shall be        satisfied that at least one of indications of chroma filter        information (e.g., alf_chroma_filter_signal_flag,        alf_cc_cb_filter_signal_flag, alf_cc_cr_filter_signal_flag) is        true.-   15. In above examples, the indication of CC-ALF filtering presence    information may be replaced from two syntax elements (e.g.,    alf_cc_cb_filter_signal_flag, alf_cc_cr_filter_signal_flag) by a    syntax element (which may be non-binary value, e.g.,    alf_cc_filter_idc).

6. Example Embodiments

Below are some example embodiments for some of the aspects summarizedabove in Section 5, which can be applied to the VVC specification. Thechanged texts are based on the latest VVC text in JVET-Q2001-vE. Mostrelevant parts that have been added or modified are

, and some of the deleted parts are marked with double brackets (e.g.,[[a]] denotes the deletion of the character of “a”).

6.1. First Set of Embodiments

This is a set of embodiments for items 1 summarized above in Section 5.

6.1.1. An Embodiment for 1.a.i

ph_scaling_list_aps_id specifies the adaptation_parameter_set_id of thescaling list APS.

The TemporalId of the APS NAL unit having aps_params_type equal toSCALING_APS and adaptation_parameter_set_id equal toph_scaling_list_aps_id shall be less than or equal to the TemporalId ofthe picture associated with PH.

. . .

scaling_list_chroma_present_flag equal to 1 specifies that chromascaling lists are present in scaling_list_data( ).scaling_list_chroma_present_flag equal to 0 specifies that chromascaling lists are not present in scaling_list_data( ). [[It is arequirement of bitstream conformance thatscaling_list_chroma_present_flag shall be equal to 0 whenChromaArrayType is equal to 0, and shall be equal to 1 whenChromaArrayType is not equal to 0.]]

6.1.2. An Embodiment for 1.a.ii

ph_scaling_list_aps_id specifies the adaptation_parameter_set_id of thescaling list APS.

The TemporalId of the APS NAL unit having aps_params_type equal toSCALING_APS and adaptation_parameter_set_id equal toph_scaling_list_aps_id shall be less than or equal to the TemporalId ofthe picture associated with PH.

(alternatively, it may be phrased as follows:

. . . scaling_list_chroma_present_flag equal to 1 specifies that chromascaling lists are present in scaling_list_data( ).scaling_list_chroma_present_flag equal to 0 specifies that chromascaling lists are not present in scaling_list_data( ). [[It is arequirement of bitstream conformance thatscaling_list_chroma_present_flag shall be equal to 0 whenChromaArrayType is equal to 0, and shall be equal to 1 whenChromaArrayType is not equal to 0.]]

6.1.3. An Embodiment for 1.b.i

ph_lmcs_aps_id specifies the adaptation_parameter_set_id of the LMCS APSthat the slices associated with the PH refers to.

The TemporalId of the APS NAL unit having aps_params_type equal toLMCS_APS and adaptation_parameter_set_id equal to ph lmcs aps id shallbe less than or equal to the TemporalId of the picture associated withPH.

6.1.4. An Embodiment for 1.b.ii

ph_lmcs_aps_id specifies the adaptation_parameter_set_id of the LMCS APSthat the slices associated with the PH refers to.

The TemporalId of the APS NAL unit having aps_params_type equal toLMCS_APS and adaptation_parameter_set_id equal to ph lmcs aps id shallbe less than or equal to the TemporalId of the picture associated withPH.

6.1.5. An Embodiment for 1.c.i

The semantics of PH syntax elements are changes as follows:

ph_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id of thei-th ALF APS that the luma component of the slices associated with thePH refers to.

The value of alf_luma_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto ph_alf_aps_id_luma[i] shall be equal to 1.

The TemporalId of the APS NAL unit having aps_params_type equal toALF_APS and adaptation_parameter_set_id equal to ph_alf_aps_id_luma[i]shall be less than or equal to the TemporalId of the picture associatedwith the PH.

. . .

The semantics of SH syntax elements are changes as follows:

. . .

slice_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id ofthe i-th ALF APS that the luma component of the slice refers to.—Whenslice_alf_enabled_flag is equal to 1 and slice_alf_aps_id_luma[i] is notpresent, the value of slice_alf_aps_id_luma[i] is inferred to be equalto the value of ph_alf_aps_id_luma[i].

The TemporalId of the APS NAL unit having aps_params_type equal toALF_APS and adaptation_parameter_set_id equal toslice_alf_aps_id_luma[i] shall be less than or equal to the TemporalIdof the coded slice NAL unit. The value of alf_luma_filter_signal_flag ofthe APS NAL unit having aps_params_type equal to ALF_APS andadaptation_parameter set id equal to slice_alf_aps_id_luma[i] shall beequal to 1.

. . .

And the semantics of the APS syntax elements in the ALF data syntaxstructure are changed as follows:

. . .

alf_chroma_filter_signal_flag equal to 1 specifies that a chroma filteris signalled. alf_chroma_filter_signal_flag equal to 0 specifies that achroma filter is not signalled. [[When ChromaArrayType is equal to 0,alf_chroma_filter_signal_flag shall be equal to 0.]]

. . . alf_cc_cb_filter_signal_flag equal to 1 specifies thatcross-component filters for the Cb colour component are signalled.alf_cc_cb_filter_signal_flag equal to 0 specifies that cross-componentfilters for Cb colour component are not signalled. [[WhenChromaArrayType is equal to 0, alf_cc_cb_filter_signal_flag shall beequal to 0.]]

alf_cc_cr_filter_signal_flag equal to 1 specifies that cross-componentfilters for the Cr colour component are signalled.alf_cc_cr_filter_signal_flag equal to 0 specifies that cross-componentfilters for the Cr colour component are not signalled. [[WhenChromaArrayType is equal to 0, alf_cc_cr_filter_signal_flag shall beequal to 0.]]

6.1.6. An Embodiment for 1.c.ii

The semantics of PH syntax elements are changes as follows:

ph_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id of thei-th ALF APS that the luma component of the slices associated with thePH refers to.

The value of alf_luma_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto ph_alf_aps_id_luma[i] shall be equal to 1.

The TemporalId of the APS NAL unit having aps_params_type equal toALF_APS and adaptation_parameter_set_id equal to ph_alf_aps_id_luma[i]shall be less than or equal R h ealoralId of the picture associated withthe PH.

ph_alf_chroma_idc equal to 0 specifies that the adaptive loop filter isnot applied to Cb and Cr colour components. ph_alf_chroma_idc equal to 1indicates that the adaptive loop filter is applied to the Cb colourcomponent. ph_alf_chroma_idc equal to 2 indicates that the adaptive loopfilter is applied to the Cr colour component. ph_alf_chroma_idc equal to3 indicates that the adaptive loop filter is applied to Cb and Cr colourcomponents. When ph_alf_chroma_idc is not present, it is inferred to beequal to 0.

. . .

The semantics of SH syntax elements are changes as follows:

. . .

slice_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id ofthe i-th ALF APS that the luma component of the slice refers to.—Whenslice_alf_enabled_flag is equal to 1 and slice_alf_aps_id_luma[i] is notpresent, the value of slice_alf_aps_id_luma[i] is inferred to be equalto the value of ph_alf_aps_id_luma[i].

The TemporalId of the APS NAL unit having aps_params_type equal toALF_APS and adaptation_parameter_set_id equal toslice_alf_aps_id_luma[i] shall be less than or equal to the TemporalIdof the coded slice NAL unit.

The value of alf_luma_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto slice_alf_aps_id_luma[i] shall be equal to 1.

. . .

And the semantics of the APS syntax elements in the ALF data syntaxstructure are changed as follows:

. . .

alf_chroma_filter_signal_flag equal to 1 specifies that a chroma filteris signalled. alf_chroma_filter_signal_flag equal to 0 specifies that achroma filter is not signalled. [[When ChromaArrayType is equal to 0,alf_chroma_filter_signal_flag shall be equal to 0.]]

. . .

alf_cc_cb_filter_signal_flag equal to 1 specifies that cross-componentfilters for the Cb colour component are signalled.alf_cc_cb_filter_signal_flag equal to 0 specifies that cross-componentfilters for Cb colour component are not signalled. [[WhenChromaArrayType is equal to 0, alf_cc_cb_filter_signal_flag shall beequal to 0.]]

alf_cc_cr_filter_signal_flag equal to 1 specifies that cross-componentfilters for the Cr colour component are signalled.alf_cc_cr_filter_signal_flag equal to 0 specifies that cross-componentfilters for the Cr colour component are not signalled. [[WhenChromaArrayType is equal to 0, alf_cc_cr_filter_signal_flag shall beequal to 0.]]

6.1.7. An Embodiment for 1.c.iii

The semantics of PH syntax elements are changes as follows:

. . .

ph_alf_aps_id_chroma specifies the adaptation_parameter_set_id of theALF APS that the chroma component of the slices associated with the PHrefers to.

The value of alf_chroma_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto ph_alf_aps_id_chroma shall be equal to 1.

. . .

ph_cc_alf_cb_aps_id specifies the adaptation_parameter_set_id of the ALFAPS that the Cb colour component of the slices associated with the PHrefers to

The value of alf_cc_cb_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto ph_cc_alf_cb_aps_id shall be equal to 1.

. . .

ph_cc_alf_cr_aps_id specifies the adaptation_parameter_set_id of the ALFAPS that the Cr colour component of the slices associated with the PHrefers to.

The value of alf_cc_cr_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto ph_cc_alf_cr_aps_id shall be equal to 1.

. . .

The semantics of SH syntax elements are changes as follows:

. . .

slice_alf_aps_id_chroma specifies the adaptation_parameter_set_id of theALF APS that the chroma component of the slice refers to. The TemporalIdof the APS NAL unit having aps_params_type equal to ALF_APS andadaptation_parameter_set_id equal to slice_alf_aps_id_chroma shall beless than or equal to the TemporalId of the coded slice NAL unit. Whenslice_alf_enabled_flag is equal to 1 and slice_alf_aps_id_chroma is notpresent, the value of slice_alf_aps_id_chroma is inferred to be equal tothe value of ph_alf_aps_id_chroma.

The value of alf_chroma_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto slice_alf_aps_id_chroma shall be equal to 1.

. . .

slice_cc_alf_cb_aps_id specifies the adaptation_parameter_set_id thatthe Cb colour component of the slice refers to.

The TemporalId of the APS NAL unit having aps_params_type equal toALF_APS and adaptation_parameter_set_id equal to slice_cc_alf_cb_aps_idshall be less than or equal to the TemporalId of the coded slice NALunit. When slice_cc_alf_cb_enabled_flag is equal to 1 andslice_cc_alf_cb_aps_id is not present, the value ofslice_cc_alf_cb_aps_id is inferred to be equal to the value ofph_cc_alf_cb_aps_id.

The value of alf_cc_cb_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto slice_cc_alf_cb_aps_id shall be equal to 1.

. . .

slice_cc_alf_cr_aps_id specifies the adaptation_parameter_set_id thatthe Cr colour component of the slice refers to. The TemporalId of theAPS NAL unit having aps_params_type equal to ALF_APS andadaptation_parameter_set_id equal to slice_cc_alf_cr_aps_id shall beless than or equal to the TemporalId of the coded slice NAL unit. Whenslice_cc_alf_cr_enabled_flag is equal to 1 and slice_cc_alf_cr_aps_id isnot present, the value of slice_cc_alf_cr_aps_id is inferred to be equalto the value of ph_cc_alf_cr_aps_id.

The value of alf_cc_cr_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto slice_cc_alf_cr_aps_id shall be equal to 1.

. . .

And the semantics of APS syntax elements are changed as follows:

. . .

alf_chroma_filter_signal_flag equal to 1 specifies that a chroma filteris signalled. alf_chroma_filter_signal_flag equal to 0 specifies that achroma filter is not signalled. [[When ChromaArrayType is equal to 0,alf_chroma_filter_signal_flag shall be equal to 0.]]

. . .

alf_cc_cb_filter_signal_flag equal to 1 specifies that cross-componentfilters for the Cb colour component are signalled.alf_cc_cb_filter_signal_flag equal to 0 specifies that cross-componentfilters for Cb colour component are not signalled. [[WhenChromaArrayType is equal to 0, alf_cc_cb_filter_signal_flag shall beequal to 0.]]

alf_cc_cr_filter_signal_flag equal to 1 specifies that cross-componentfilters for the Cr colour component are signalled.alf_cc_cr_filter_signal_flag equal to 0 specifies that cross-componentfilters for the Cr colour component are not signalled. [[WhenChromaArrayType is equal to 0, alf_cc_cr_filter_signal_flag shall beequal to 0.]]

. . .

6.1.8. An Embodiment for 1.d.i

The semantics of APS syntax elements in the ALF data syntax structureare changed as follows:

. . .

alf_chroma_filter_signal_flag equal to 1 specifies that a chroma filteris signalled. alf_chroma_filter_signal_flag equal to 0 specifies that achroma filter is not signalled. [[When ChromaArrayType is equal to 0,alf_chroma_filter_signal_flag shall be equal to 0.]]

. . .

alf_cc_cb_filter_signal_flag equal to 1 specifies that cross-componentfilters for the Cb colour component are signalled.alf_cc_cb_filter_signal_flag equal to 0 specifies that cross-componentfilters for Cb colour component are not signalled. [[WhenChromaArrayType is equal to 0, alf_cc_cb_filter_signal_flag shall beequal to 0.]]

alf_cc_cr_filter_signal_flag equal to 1 specifies that cross-componentfilters for the Cr colour component are signalled.alf_cc_cr_filter_signal_flag equal to 0 specifies that cross-componentfilters for the Cr colour component are not signalled. [[WhenChromaArrayType is equal to 0, alf_cc_cr_filter_signal_flag shall beequal to 0.]]

. . .

6.1.9. An Embodiment for 1.d.ii

The semantics of APS syntax elements in the SCALING LIST data syntaxstructure are changed as follows:

. . .

scaling_list_chroma_present_flag equal to 1 specifies that chromascaling lists are present in scaling_list_data( ).scaling_list_chroma_present_flag equal to 0 specifies that chromascaling lists are not present in scaling_list_data( ). [[It is arequirement of bitstream conformance thatscaling_list_chroma_present_flag shall be equal to 0 whenChromaArrayType is equal to 0, and shall be equal to 1 whenChromaArrayType is not equal to 0.

. . . ]]

6.1.10. An Embodiment for 1.e and 1.f

ph_scaling_list_aps_id specifies the adaptation_parameter_set_id of thescaling list APS.

:

-   -   The TemporalId of the APS NAL unit having aps_params_type equal        to SCALING_APS and adaptation_parameter_set_id equal to        ph_scaling_list_aps_id shall be less than or equal to the        TemporalId of the picture associated with PH.

. . .

ph_lmcs_aps_id specifies the adaptation_parameter_set_id of the LMCS APSthat the slices associated with the PH refers to.

:

-   -   The TemporalId of the APS NAL unit having aps_params_type equal        to LMCS_APS and adaptation_parameter_set_id equal to        ph_lmcs_aps_id shall be less than or equal to the TemporalId of        the picture associated with PH.

. . .

ph_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id of thei-th ALF APS that the luma component of the slices associated with thePH refers to.

-   -   The value of alf_luma_filter_signal_flag of the APS NAL unit        having aps_params_type equal to ALF_APS and        adaptation_parameter_set_id equal to ph_alf_aps_id_luma[i] shall        be equal to 1.    -   The TemporalId of the APS NAL unit having aps_params_type equal        to ALF_APS and adaptation_parameter_set_id equal to        ph_alf_aps_id_luma[i] shall be less than or equal to the        TemporalId of the picture associated with the PH.

ph_alf_chroma_idc equal to 0 specifies that the adaptive loop filter isnot applied to Cb and Cr colour components. ph_alf_chroma_idc equal to 1indicates that the adaptive loop filter is applied to the Cb colourcomponent. ph_alf_chroma_idc equal to 2 indicates that the adaptive loopfilter is applied to the Cr colour component. ph_alf_chroma_idc equal to3 indicates that the adaptive loop filter is applied to Cb and Cr colourcomponents. When ph_alf_chroma_idc is not present, it is inferred to beequal to 0.

ph_alf_aps_id_chroma specifies the adaptation_parameter_set_id of theALF APS that the chroma component of the slices associated with the PHrefers to.

-   -   The value of alf_chroma_filter_signal_flag of the APS NAL unit        having aps_params_type equal to ALF_APS and        adaptation_parameter_set_id equal to ph_alf_aps_id_chroma shall        be equal to 1.    -   The TemporalId of the APS NAL unit having aps_params_type equal        to ALF_APS and adaptation_parameter_set_id equal to        ph_alf_aps_id_chroma shall be less than or equal to the        TemporalId of the picture associated with the PH.

. . .

ph_cc_alf_cb_aps_id specifies the adaptation_parameter_set_id of the ALFAPS that the Cb colour component of the slices associated with the PHrefers to.

-   -   The value of alf_cc_cb_filter_signal_flag of the APS NAL unit        having aps_params_type equal to ALF_APS and        adaptation_parameter_set_id equal to ph_cc_alf_cb_aps_id shall        be equal to 1.    -   The TemporalId of the APS NAL unit having aps_params_type equal        to ALF_APS and adaptation_parameter_set_id equal to        ph_cc_alf_cb_aps_id shall be less than or equal to the        TemporalId of the picture associated with the PH.

. . .

ph_cc_alf_cr_aps_id specifies the adaptation_parameter_set_id of the ALFAPS that the Cr colour component of the slices associated with the PHrefers to.

-   -   The value of alf_cc_cr_filter_signal_flag of the APS NAL unit        having aps_params_type equal to ALF_APS and        adaptation_parameter_set_id equal to ph_cc_alf_cr_aps_id shall        be equal to 1.    -   The TemporalId of the APS NAL unit having aps_params_type equal        to ALF_APS and adaptation_parameter_set_id equal to        ph_cc_alf_cr_aps_id shall be less than or equal to the        TemporalId of the picture associated with the PH.

. . .

slice_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id ofthe i-th ALF APS that the luma component of the slice refers to.—Whenslice_alf_enabled_flag is equal to 1 and slice_alf_aps_id_luma[i] is notpresent, the value of slice_alf_aps_id_luma[i] is inferred to be equalto the value of ph_alf_aps_id_luma[i].

-   -   The TemporalId of the APS NAL unit having aps_params_type equal        to ALF_APS and adaptation_parameter_set_id equal to        slice_alf_aps_id_luma[i] shall be less than or equal to the        TemporalId of the coded slice NAL unit.    -   The value of alf_luma_filter_signal_flag of the APS NAL unit        having aps_params_type equal to ALF_APS and        adaptation_parameter_set_id equal to slice_alf_aps_id_luma[i]        shall be equal to 1.

. . .

slice_alf_aps_id_chroma specifies the adaptation_parameter_set_id of theALF APS that the chroma component of the slice refers to. Whenslice_alf_enabled_flag is equal to 1 and slice_alf_aps_id_chroma is notpresent, the value of slice_alf_aps_id_chroma is inferred to be equal tothe value of ph_alf_aps_id_chroma.

-   -   The TemporalId of the APS NAL unit having aps_params_type equal        to ALF_APS and adaptation_parameter_set_id equal to        slice_alf_aps_id_chroma shall be less than or equal to the        TemporalId of the coded slice NAL unit.    -   The value of alf_chroma_filter_signal_flag of the APS NAL unit        having aps_params_type equal to ALF_APS and        adaptation_parameter_set_id equal to slice_alf_aps_id_chroma        shall be equal to 1.

. . .

slice_cc_alf_cb_aps_id specifies the adaptation_parameter_set_id thatthe Cb colour component of the slice refers to.

When slice_cc_alf_cb_enabled_flag is equal to 1 andslice_cc_alf_cb_aps_id is not present, the value ofslice_cc_alf_cb_aps_id is inferred to be equal to the value ofph_cc_alf_cb_aps_id.

-   -   The TemporalId of the APS NAL unit having aps_params_type equal        to ALF_APS and adaptation_parameter_set_id equal to        slice_cc_alf_cb_aps_id shall be less than or equal to the        TemporalId of the coded slice NAL unit.    -   The value of alf_cc_cb_filter_signal_flag of the APS NAL unit        having aps_params_type equal to ALF_APS and        adaptation_parameter_set_id equal to slice_cc_alf_cb_aps_id        shall be equal to 1.

. . .

slice_cc_alf_cr_aps_id specifies the adaptation_parameter_set_id thatthe Cr colour component of the slice refers to. Whenslice_cc_alf_cr_enabled_flag is equal to 1 and slice_cc_alf_cr_aps_id isnot present, the value of slice_cc_alf_cr_aps_id is inferred to be equalto the value of ph_cc_alf_cr_aps_id.

-   -   The TemporalId of the APS NAL unit having aps_params_type equal        to ALF_APS and adaptation_parameter_set_id equal to        slice_cc_alf_cr_aps_id shall be less than or equal to the        TemporalId of the coded slice NAL unit.    -   The value of alf_cc_cr_filter_signal_flag of the APS NAL unit        having aps_params_type equal to ALF_APS and        adaptation_parameter_set_id equal to slice_cc_alf_cr_aps_id        shall be equal to 1.

. . .

6.1.11. An Embodiment for 1.g

The semantics of SH syntax elements are changes as follows:

slice_alf_aps_id_chroma specifies the adaptation_parameter_set_id of theALF APS that the chroma component of the slice refers to. The TemporalIdof the APS NAL unit having aps_params_type equal to ALF_APS andadaptation_parameter_set_id equal to slice_alf_aps_id_chroma shall beless than or equal to the TemporalId of the coded slice NAL unit. Whenslice_alf_enabled_flag is equal to 1 and slice_alf_aps_id_chroma is notpresent

the value of slice_alf_aps_id_chroma is inferred to be equal to thevalue of ph_alf_aps_id_chroma.

. . .

slice_cc_alf_cb_aps_id specifies the adaptation_parameter_set_id thatthe Cb colour component of the slice refers to.

The TemporalId of the APS NAL unit having aps_params_type equal toALF_APS and adaptation_parameter_set_id equal to slice_cc_alf_cb_aps_idshall be less than or equal to the TemporalId of the coded slice NALunit. When slice_cc_alf_cb_enabled_flag is equal to 1 andslice_cc_alf_cb_aps_id is not present

the value of slice_cc_alf_cb_aps_id is inferred to be equal to the valueof ph_cc_alf_cb_aps_id.

. . .

slice_cc_alf_cr_aps_id specifies the adaptation_parameter_set_id thatthe Cr colour component of the slice refers to. The TemporalId of theAPS NAL unit having aps_params_type equal to ALF_APS andadaptation_parameter_set_id equal to slice_cc_alf_cr_aps_id shall beless than or equal to the TemporalId of the coded slice NAL unit. Whenslice_cc_alf_cr_enabled_flag is equal to 1 and slice_cc_alf_cr_aps_id isnot present

the value of slice_cc_alf_cr_aps_id is inferred to be equal to the valueof ph_cc_alf_cr_aps_id.

6.2. Second Set of Embodiments

This is a set of embodiments for items 2 (from 2.a to 2.c) summarizedabove in Section 5.

The syntax structure pic_parameter_set_rbsp( ) is changed as follows:

Descriptor pic_parameter_set_rbsp( ) {  pps_pic_parameter_set_id ue(v) .. .  deblocking_filter_[[control_present_flag]] 

u([[1]] 

 )  if(deblocking_filter_[[control_present_flag]] 

  ) {  [[deblocking_filter_override_enabled_flag]] [[u(1)]]  [[pps_deblocking_filter_disabled_flag]] [[u(1)]]   [[if(!pps_deblocking_filter_disabled_flag ) { }]    pps_beta_offset_div2se(v)    pps_tc_offset_div2 se(v)    pps_cb_beta_offset_div2 se(v)   pps_cb_tc_offset_div2 se(v)    pps_cr_beta_offset_div2 se(v)   pps_cr_tc_offset_div2 se(v)   [[}]]  }  [[rpl_info_in_ph_flag]][[u(1)]]  if( deblocking_filter_[[override_enabled_flag]] 

  )   

 

. . .

[[deblocking_filter_control_present_flag equal to 1 specifies thepresence of deblocking filter control syntax elements in the PPS.deblocking_filter_control_present_flag equal to 0 specifies the absenceof deblocking filter control syntax elements in the PPS.

deblocking_filter_override_enabled_flag equal to 1 specifies thepresence of ph_deblocking_filter_override_flag in the PHs referring tothe PPS or slice_deblocking_filter_override_flag in the slice headersreferring to the PPS. deblocking_filter_override_enabled_flag equal to 0specifies the absence of ph_deblocking_filter_override_flag in PHsreferring to the PPS or slice_deblocking_filter_override_flag in sliceheaders referring to the PPS. When not present, the value ofdeblocking_filter_override_enabled_flag is inferred to be equal to 0.

pps_deblocking_filter_disabled_flag equal to 1 specifies that theoperation of deblocking filter is not applied for slices referring tothe PPS in which slice_deblocking_filter_disabled_flag is not present.pps_deblocking_filter_disabled_flag equal to 0 specifies that theoperation of the deblocking filter is applied for slices referring tothe PPS in which slice_deblocking_filter_disabled_flag is not present.When not present, the value of pps_deblocking_filter_disabled_flag isinferred to be equal to 0.]]

dbf_info_in_ph_flag equal to 1 specifies that deblocking filterinformation is present in the PH syntax structure and not present inslice headers referring to the PPS that do not contain a PH syntaxstructure. dbf_info_in_ph_flag equal to 0 specifies that deblockingfilter information is not present in the PH syntax structure and may bepresent in slice headers referring to the PPS that do not contain a PHsyntax structure. [[When not present, the value of dbf_info_in_ph_flagis inferred to be equal to 0.]]

. . .

And the syntax structure picture_header_structure( ) is changed asfollows:

Descriptor picture_header_structure( ) {  gdr_or_irap_pic_flag u(1) . ..   if( deblocking_filter_[[override_enabled_flag]] 

  && dbf_info_in_ph_flag ) {    ph_deblocking_filter_[[override]] 

 _flag u(1)    if( ph_deblocking_filter_[[override]] 

 _flag ) {  ph_deblocking_[[filter_disabled]] 

 _flag u(1)     if( [[!]]ph_deblocking_[[filter_disabled]] 

 _flag ) {      ph_beta_offset_div2 se(v)      ph_tc_offset_div2 se(v)     ph_cb_beta_offset_div2 se(v)      ph_cb_tc_offset_div2 se(v)     ph_cr_beta_offset_div2 se(v)      ph_cr_tc_offset_div2 se(v)    }  }  } . . .

ph_deblocking_filter_used_flag equal to 1 specifies that the deblockingfilter is applied for the slices in the current picture.ph_deblocking_filter_used_flag equal to 0 species that the deblockingfilter is not applied for the slices in the current picture. When notpresent, the value of ph_deblocking_filter_used_flag is inferred to beequal to (deblocking_filter_mode_idc>0).

ph_deblocking_[[filter]]parameters_override_flag equal to 1 specifiesthat deblocking parameters are present in the PH.ph_deblocking_[[filter]]parameters_override_flag equal to 0 specifiesthat deblocking parameters are not present in the PH. When not present,the value of ph_deblocking_filter_override_flag is inferred to be equalto 0.

[[ph_deblocking_filter_disabled_flag equal to 1 specifies that theoperation of the deblocking filter is not applied for the slicesassociated with the PH. ph_deblocking_filter_disabled_flag equal to 0specifies that the operation of the deblocking filter is applied for theslices associated with the PH. When ph_deblocking_filter_disabled_flagis not present, it is inferred to be equal topps_deblocking_filter_disabled_flag.]]

. . .

And the syntax structure slice_header( ) is changed as follows:

Descriptor slice_header( ) {  picture_header_in_slice_header_flag u(1) .. .   if( deblocking_filter_[[override_enabled_flag]] 

  && !dbf_info_in_ph_flag )    slice_deblocking_filter[[override]] 

 _flag u(1)   if( slice_deblocking_filter_[[override]] 

 _flag ) {    slice_deblocking_[[filter_disabled]] 

 _flag u(1)    if( [[!]]slice_deblocking_[[filter_disabled]] 

 _flag ) {     slice_beta_offset_div2 se(v)     slice_tc_offset_div2se(v)     slice_cb_beta_offset_div2 se(v)     slice_cb_tc_offset_div2se(v)     slice_cr_beta_offset_div2 se(v)     slice_cr_tc_offset_div2se(v)    }   } . . .

slice_deblocking_[[filter]]parameters_override_flag equal to 1 specifiesthat deblocking parameters are present in the slice header.slice_deblocking_[[filter]]

_override_flag equal to 0 specifies that deblocking parameters are notpresent in the slice header. When not present, the value ofslice_deblocking_filter_override_flag is inferred to be equal to[[ph_deblocking_filter_override_flag]]0.

[[slice_deblocking_filter_disabled_flag equal to 1 specifies that theoperation of the deblocking filter is not applied for the current slice.slice_deblocking_filter_disabled_flag equal to 0 specifies that theoperation of the deblocking filter is applied for the current slice.When slice_deblocking_filter_disabled_flag is not present, it isinferred to be equal to ph_deblocking_filter_disabled_flag.]]

. . .

And the decoding process of deblocking filter process is changed asfollows:

8.8.3 Deblocking Filter Process 8.8.3.1 General

The deblocking filter process is applied to all coding subblock edgesand transform block edges of a picture, except the following types ofedges:

-   -   Edges that are at the boundary of the picture,    -   Edges that coincide with the boundaries of a subpicture with        subpicture index subpicIdx and        loop_filter_across_subpic_enabled_flag[subpicIdx] is equal to 0,    -   Edges that coincide with the virtual boundaries of the picture        when VirtualBoundariesPresentFlag is equal to 1,    -   Edges that coincide with tile boundaries when        loop_filter_across_tiles_enabled_flag is equal to 0,    -   Edges that coincide with slice boundaries when        loop_filter_across_slices_enabled_flag is equal to 0,    -   Edges that coincide with upper or left boundaries of slices with        slice_deblocking_filter_        [[disabled]]_flag equal to [[1]]        .    -   Edges within slices with slice_deblocking_filter_        [[disabled]]_flag equal to [[1]]        ,    -   Edges that do not correspond to 4×4 sample grid boundaries of        the luma component,    -   Edges that do not correspond to 8×8 sample grid boundaries of        the chroma component,    -   Edges within the luma component for which both sides of the edge        have intra_bdpcm_luma_flag equal to 1,    -   Edges within the chroma components for which both sides of the        edge have intra_bdpcm_chroma_flag equal to 1,    -   Edges of chroma subblocks that are not edges of the associated        transform unit.

The edge type, vertical or horizontal, is represented by the variableedgeType as specified in Table 42.

TABLE 42 Name of association to edgeType edgeType Name of edgeType 0(vertical edge) EDGE_VER 1 (horizontal edge) EDGE_HOR

When slice_deblocking_filter_

[[disabled]]_flag of the current slice is equal to [[0]]

, the following applies:

-   -   The variable treeType is set equal to DUAL_TREE_LUMA.    -   The vertical edges are filtered by invoking the deblocking        filter process for one direction as specified in clause 8.8.3.2        with the variable treeType, the reconstructed picture prior to        deblocking, i.e., the array recPicture_(L) and the variable        edgeType set equal to EDGE_VER as inputs, and the modified        reconstructed picture after deblocking, i.e., the array        recPicture_(L) as outputs.    -   The horizontal edge are filtered by invoking the deblocking        filter process for one direction as specified in clause 8.8.3.2        with the variable treeType, the modified reconstructed picture        after deblocking, i.e., the array recPicture_(L) and the        variable edgeType set equal to EDGE_HOR as inputs, and the        modified reconstructed picture after deblocking, i.e., the array        recPicture_(L) as outputs.    -   When ChromaArrayType is not equal to 0, the following applies:        -   The variable treeType is set equal to DUAL_TREE_CHROMA        -   The vertical edges are filtered by invoking the deblocking            filter process for one direction as specified in clause            8.8.3.2 with the variable treeType, the reconstructed            picture prior to deblocking, i.e., the arrays            recPicture_(Cb) and recPicture_(Cr), and the variable            edgeType set equal to EDGE_VER as inputs, and the modified            reconstructed picture after deblocking, i.e., the arrays            recPicture_(Cb) and recPicture_(Cr) as outputs.        -   The horizontal edge are filtered by invoking the deblocking            filter process for one direction as specified in clause            8.8.3.2 with the variable treeType, the modified            reconstructed picture after deblocking, i.e., the arrays            recPicture_(Cb) and recPicture_(Cr), and the variable            edgeType set equal to EDGE_HOR as inputs, and the modified            reconstructed picture after deblocking, i.e., the arrays            recPicture_(Cb) and recPicture_(Cr) as outputs.

6.3. Third Set of Embodiments

The changes, marked in boldfaced italics, are based on JVET-Q2001-vE.

The i-th chroma QP mapping table ChromaQpTable[i] for i=0 . . .numQpTables−1 is derived as follows:

qpInVal[ i ][ 0 ] = qp_table_start_minus26[ i ] + 26 qpOutVal[ i ][ 0 ]= qpInVal[ i ][ 0 ] for( j = 0; j <= num_points_in_qp_table_minus1[ i ];j++ ) {  qpInVal[ i ][ j + 1 ] = qpInVal[ i ][ j ] +delta_qp_in_val_minus1[  i ][ j ] + 1  qpOutVal[ i ][ j + 1 ] =qpOutVal[ i ][ j ] +  ( 

 delta_qp_in_val_minus1[ i ][ j ] + 

  {circumflex over ( )} delta_qp_diff_val[ i ][ j ] ) } ChromaQpTable[ i][ qpInVal[ i ][ 0 ] ] = qpOutVal[ i ][ 0 ] for( k = qpInVal[ i ][ 0 ] −1; k >= −QpBdOffset; k − − )  ChromaQpTable[ i ][ k ] = Clip3(−QpBdOffset, 63,  ChromaQpTable[ i ][ k + 1 ] − 1 ) for( j = 0; j <=num_points_in_qp_table_minus1[ i ]; j++ ) {  sh = (delta_qp_in_val_minus1[ i ][j ] + 1 ) >> 1  for( k = qpInVal[ i ][ j ] +1, m = 1; k <= qpInval[ i ][ j + 1 ]; k++,  m++ )   ChromaQpTable[ i ][k ] = ChromaQpTable[ i ][ qpInVal[ i ][ j ] ] +    ( ( qpOutVal[ i ][j +1] − qpOutVal[ i ][j ] ) * m + sh ) / ( delta_qp_in_val_minus1[ i ][j] +1 ) } for( k = qpInVal[ i ][ num_points_in_qp_table_minus1[ i ] + 1 ] +1; k <= 63; k++ )  ChromaQpTable[ i ][ k ] = Clip3( −QpBdOffset, 63, ChromaQpTable[ i ][ k − 1 ] + 1 )

When same_qp_table_for_chroma is equal to 1, ChromaQpTable[1][k] andChromaQpTable[2][k] are set equal to ChromaQpTable[0][k] for k in therange of −QpBdOffset to 63, inclusive.

It is a requirement of bitstream conformance that the values ofqpInVal[i][j] and qpOutVal[i][j] shall be in the range of −QpBdOffset to63, inclusive for i in the range of 0 to numQpTables−1, inclusive, and jin the range of 0 to num_points_in_qp_table_minus1[i]+1, inclusive.

6.4. Fourth Embodiment

PPS semantics (based on the text in JVET-R0159-v2, excluding the SPSflag):

. . .

deblocking_filter_control_present_flag equal to 1 specifies the presenceof deblocking filter control syntax elements in the PPS.deblocking_filter_contol_present_flag equal to 0 specifies the absenceof deblocking filter control syntax elements in the PPS

deblocking_filter_override_enabled_flag equal to 1 specifies thepresence of ph_deblocking_filter_override_flag in the PHs referring tothe PPS or slice_deblocking_filter_override_flag in the slice headersreferring to the PPS. deblocking_filter_override_enabled_flag equal to 0specifies the absence of ph_deblocking_filter_override_flag in PHsreferring to the PPS or slice_deblocking_filter_override_flag in sliceheaders referring to the PPS. When not present, the value ofdeblocking_filter_override_enabled_flag is inferred to be equal to 0.

[[pps_deblocking_filter_disabled_flag equal to 1 specifies that theoperation of deblocking filter is not applied for slices referring tothe PPS of which slice_deblocking_filter_disabled_flag andph_deblocking_filter_disabled_flag are not present.pps_deblocking_filter_disabled_flag equal to 0 specifies that theoperation of the deblocking filter is applied for slices referring tothe PPS of which slice_deblocking_filter_disabled_flag andph_deblocking_filter_disabled_flag are not present. When not present,the value of pps_deblocking_filter_disabled_flag is inferred to be equalto 0.

Or

pps_deblocking_filter_disabled_flag equal to 1 specifies that theoperation of deblocking filter is not applied for slices referring tothe PPS when deblocking_filter_override_enabled_flag is equal to 0.pps_deblocking_filter_disabled_flag equal to 0 specifies that theoperation of the deblocking filter is applied for slices referring tothe PPS when deblocking_filter_override_enabled_flag is equal to 0. Whennot present, the value of pps_deblocking_filter_disabled_flag isinferred to be equal to 0.]]

. . .

The syntax structure picture_header_structure( ) is changed as follows:

Descriptor picture_header_structure( ) {  gdr_or_irap_pic_flag u(1) . ..  if( deblocking_filter_override_enabled_flag && dbf_info_in_ph_flag ){   ph_deblocking_filter_override_flag u(1)   if(ph_deblocking_filter_override_flag ) {    

    ph_deblocking_filter_disabled_flag u(1)    if(!ph_deblocking_filter_disabled_flag ) {     ph_beta_offset_div2 se(v)    ph_tc_offset_div2 se(v)     ph_cb_beta_offset_div2 se(v)    ph_cb_tc_offset_div2 se(v)     ph_cr_beta_offset_div2 se(v)    ph_cr_tc_offset_div2 se(v)    }   }  } . . .

ph_deblocking_filter_override_flag equal to 1 specifies that deblockingparameters are present in the PH. ph_deblocking_filter_override_flagequal to 0 specifies that deblocking parameters are not present in thePH. When not present, the value of ph_deblocking_filter_override_flag isinferred to be equal to 0.

ph_deblocking_filter_disabled_flag equal to 1 specifies that theoperation of the deblocking filter is not applied for the slicesassociated with the PH [[in which slice_deblocking_filter_disabled_flagis not present [note: When ph_deblocking_filter_disabled_flag is presentslice_deblocking_filter_disabled_flag won't be present in the SH of anyslice of the picture, therefore the removal.]]].ph_deblocking_filter_disabled_flag equal to 0 specifies that theoperation of the deblocking filter is applied for the slices associatedwith the PH [[in which slice_deblocking_filter_disabled_flag is notpresent [note: When ph_deblocking_filter_disabled_flag is present,slice_deblocking_filter_disabled_flag won't be present in the SH ofanyslice of the picture, therefore the removal.]]]. Whenph_deblocking_filter_disabled_flag is not present, it is inferred asfollows:

-   -   

    -   to be equal to pps_deblocking_filter_disabled_flag.

. . .

And the syntax structure slice_header( ) is changed as follows:

Descriptor slice_header( ) {  picture_header_in_slice_header_flag u(1) .. .  if( deblocking_filter_override_enabled_flag && !dbf_info_in_ph_flag)   slice_deblocking_filter_override_flag u(1)  if(slice_deblocking_filter_override_flag ) {   

   slice_deblocking_filter_disabled_flag u(1)   if(!slice_deblocking_filter_disabled_flag ) {    slice_beta_offset_div2se(v)    slice_tc_offset_div2 se(v)    slice_cb_beta_offset_div2 se(v)   slice_cb_tc_offset_div2 se(v)    slice_cr_beta_offset_div2 se(v)   slice_cr_tc_offset_div2 se(v)   }  } . . .

slice_deblocking_filter_override_flag equal to 1 specifies thatdeblocking parameters are present in the slice header.slice_deblocking_filter_override_flag equal to 0 specifies thatdeblocking parameters are not present in the slice header. When notpresent, the value of slice_deblocking_filter_override_flag is inferredto be equal to [[ph_deblocking_filter_override_flag]]0.

slice_deblocking_filter_disabled_flag equal to 1 specifies that theoperation of the deblocking filter is not applied for the current slice.slice_deblocking_filter_disabled_flag equal to 0 specifies that theoperation of the deblocking filter is applied for the current slice.

When slice_deblocking_filter_disabled_flag is not present, it isinferred as follows:

-   -   

    -   to be equal to ph_deblocking_filter_disabled_flag.

6.5. Fifth Embodiment

The changes marked in

, are based on JVET-P2001-vE.

Descriptor coding_unit( x0, y0, cbWidth, cbHeight, cqtDepth, treeType,modeType ) {  chType = treeType = = DUAL_TREE_CHROMA ? 1 : 0  if(slice_type != I | |  

  sps_ibc_enabled_flag  

   

  ){   if( treeType != DUAL_TREE_CHROMA &&     ( ( !( cbWidth = = 4 &&cbHeight = = 4 ) &&     modeType != MODE_TYPE_INTRA ) | |     (sps_ibc_enabled_flag && cbWidth <= 64 && cbHeight <= 64 ) ) )   cu_skip_flag[ x0 ] [ y0 ] ae(v)  if( cu_skip_flag[ x0 ] [ y0 ] = = 0&& slice_type != I &&     !( cbWidth = = 4 && cbHeight = = 4 ) &&modeType = = MODE_TYPE_ALL) pred_mode_flag ae(v)   if( ( ( slice_type == I && cu_skip_flag[ x0 ] [ y0 ] = =0 ) | |     ( slice_type != I && (CuPredMode[ chType ][ x0 ][ y0 ] != MODE_INTRA | |     ( ( ( cbWidth = =4 && cbHeight = = 4 ) modeType = = MODE_TYPE_INTRA )      &&cu_skip_flag[ x0 ][ y0 ] = = 0 ) ) ) ) &&     cbWidth <= 64 && cbHeight<= 64 && modeType != MODE_TYPE_INTER &&     sps_ibc_enabled_flag &&treeType != DUAL_TREE_CHROMA )    pred_mode_ibc_flag ae(v)  } . . . }

6.6. Sixth Embodiment 7.3.2.5 Adaptation Parameter Set RBSP Syntax

Descriptor adaptation_parameter_set_rbsp( ) { adaptation_parameter_set_id u(5)  aps_params_type u(3)  

 if( aps_params_type = = ALF_APS )   alf_data( )  else if(aps_params_type = = LMCS_APS )   lmcs_data( )  else if( aps_params_type= = SCALING_APS )   scaling_list_data( )  aps_extension_flag u(1)  if(aps_extension_flag)   while( more_rbsp_data( ) )   aps_extension_data_flag u(1)  rbsp_trailing_bits( ) }

7.3.2.19 Adaptive Loop Filter Data Syntax

Descriptor alf_data( ) {  alf_luma_filter_signal_flag u(1)  

  alf_chroma_filter_signal_flag u(1)   alf_cc_cb_filter_signal_flag u(1)  alf_cc_cr_filter_signal_flag u(1)  

. . .

7.3.2.20 Luma Mapping with Chroma Scaling Data Syntax

Descriptor lmcs_data( ) {  lmcs_min_bin_idx ue(v) lmcs_delta_max_bin_idx ue(v)  lmcs_delta_cw_prec_minus1 ue(v)  for( i =lmcs_min_bin_idx; i <= LmcsMaxBinIdx; i++ ) {   lmcs_delta_abs_cw[ i ]u(v)   if( lmcs_delta_abs_cw[ i ] > 0 )    lmcs_delta_sign_cw_flag[ i ]u(1)  }  

  lmcs_delta_abs_crs u(3)  if( lmcs_delta_abs_crs > 0 )  lmcs_delta_sign_crs_flag u(1) }

7.3.2.21 Scaling List Data Syntax

Descriptor scaling_list_data( ) {  scaling_matrix_for_lfnst_disabled_flag u(1) [[scaling_list_chroma_present_flag]]   for( id = 0; id < 28; id ++ )   matrixSize =( id < 2 ) ? 2 : ( ( id < 8 ) ? 4 : 8 )    if(  

 [[scaling_list_chroma_present_flag]] | | ( id % 3 = = 2 ) | | ( id = =27 ) ) {     scaling_list_copy_mode_flag[ id ] u(1)     if(!scaling_list_copy_mode_flag[ id ] )      scaling_list_pred_mode_flag[id ] u(1)     if( ( scaling_list_copy_mode_flag[ id ] | |scaling_list_pred_mode_flag[ id ] ) &&       id != 0 && id != 2 && id !=8 )      scaling_list_pred_id_delta[ id ] ue(v)     if(!scaling_list_copy_mode_flag[ id ] ) {      nextCoef = 0      if( id >13 ) {       scaling_list_dc_coef[ id − 14 ] se(v)       nextCoef +=scaling_list_dc_coef[ id − 14 ]      }      for( i = 0; i < matrixSize *matrixSize; i++ ) {       x = DiagScanOrder[ 3 ][ 3 ][ i ][ 0 ]       y= DiagScanOrder[ 3 ][ 3 ][ i ][ 1 ]       if( !( id > 25 && x >= 4 &&y >= 4 ) ) {        scaling_list_delta_coef[ id ][ i ] se(v)       nextCoef += scaling_list_delta_coef[ id ][ i ]       }      ScalingList[ id ][ i ] = nextCoef      }     }    }   } }

And the PH semantics are changed as follows:

. . .

ph_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id of thei-th ALF APS that the luma component of the slices associated with thePH refers to.

The value of alf_luma_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto ph_alf_aps_id_luma[i] shall be equal to 1.

The TemporalId of the APS NAL unit having aps_params_type equal toALF_APS and adaptation_parameter_set_id equal to ph_alf_aps_id_luma[i]shall be less than or equal to the TemporalId of the picture associatedwith the PH.

. . .

ph_lmcs_aps_id specifies the adaptation_parameter_set_id of the LMCS APSthat the slices associated with the PH refers to. The TemporalId of theAPS NAL unit having aps_params_type equal to LMCS_APS andadaptation_parameter_set_id equal to ph_lmcs_aps_id shall be less thanor equal to the TemporalId of the picture associated with PH.

. . .

ph_scaling_list_aps_id specifies the adaptation_parameter_set_id of thescaling list APS. The TemporalId of the APS NAL unit havingaps_params_type equal to SCALING_APS and adaptation_parameter_set_idequal to ph_scaling_list_aps_id shall be less than or equal to theTemporalId of the picture associated with PH.

And the PH semantics are changed as follows:

slice_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id ofthe i-th ALF APS that the luma component of the slice refers to. TheTemporalId of the APS NAL unit having aps_params_type equal to ALF_APSand adaptation_parameter_set_id equal to slice_alf_aps_id_luma[i] shallbe less than or equal to the TemporalId of the coded slice NAL unit.When slice_alf_enabled_flag is equal to 1 and slice_alf_aps_id_luma[i]is not present, the value of slice_alf_aps_id_luma[i] is inferred to beequal to the value of ph_alf_aps_id_luma[i].

The value of alf_luma_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto slice_alf_aps_id_luma[i] shall be equal to 1.

. . .

And the ALF data semantics are changed as follows:

alf_luma_filter_signal_flag equal to 1 specifies that a luma filter setis signalled. alf_luma_filter_signal_flag equal to 0 specifies that aluma filter set is not signalled.

alf_chroma_filter_signal_flag equal to 1 specifies that a chroma filteris signalled. alf_chroma_filter_signal_flag equal to 0 specifies that achroma filter is not signalled.

[[When ChromaArrayType is equal to 0, alf_chroma_filter_signal_flagshall be equal to 0.]]

alf_cc_cb_filter_signal_flag equal to 1 specifies that cross-componentfilters for the Cb colour component are signalled.alf_cc_cb_filter_signal_flag equal to 0 specifies that cross-componentfilters for Cb colour component are not signalled.

[[When ChromaArrayType is equal to 0, alf_cc_cb_filter_signal_flag shallbe equal to 0.]]

alf_cc_cr_filter_signal_flag equal to 1 specifies that cross-componentfilters for the Cr colour component are signalled.alf_cc_cr_filter_signal_flag equal to 0 specifies that cross-componentfilters for the Cr colour component are not signalled.

[[When ChromaArrayType is equal to 0, alf_cc_cr_filter_signal_flag shallbe equal to 0.]]

. . .

And the SCALING data semantics are changed as follows:

. . .

[[scaling_list_chroma_present_flag equal to 1 specifies that chromascaling lists are present in scaling_list_data( ).scaling_list_chroma_present_flag equal to 0 specifies that chromascaling lists are not present in scaling_list_data( ). It is arequirement of bitstream conformance thatscaling_list_chroma_present_flag shall be equal to 0 whenChromaArrayType is equal to 0, and shall be equal to 1 whenChromaArrayType is not equal to 0.]]

. . .

FIG. 1 is a block diagram showing an example video processing system1900 in which various techniques disclosed herein may be implemented.Various implementations may include some or all of the components of thesystem 1900. The system 1900 may include input 1902 for receiving videocontent. The video content may be received in a raw or uncompressedformat, e.g., 8 or 10 bit multi-component pixel values, or may be in acompressed or encoded format. The input 1902 may represent a networkinterface, a peripheral bus interface, or a storage interface. Examplesof network interface include wired interfaces such as Ethernet, passiveoptical network (PON), etc. and wireless interfaces such as wirelessfidelity (Wi-Fi) or cellular interfaces.

The system 1900 may include a coding component 1904 that may implementthe various coding or encoding methods described in the presentdisclosure. The coding component 1904 may reduce the average bitrate ofvideo from the input 1902 to the output of the coding component 1904 toproduce a coded representation of the video. The coding techniques aretherefore sometimes called video compression or video transcodingtechniques. The output of the coding component 1904 may be eitherstored, or transmitted via a communication connected, as represented bythe component 1906. The stored or communicated bitstream (or coded)representation of the video received at the input 1902 may be used bythe component 1908 for generating pixel values or displayable video thatis sent to a display interface 1910. The process of generatinguser-viewable video from the bitstream representation is sometimescalled video decompression. Furthermore, while certain video processingoperations are referred to as “coding” operations or tools, it will beappreciated that the coding tools or operations are used at an encoderand corresponding decoding tools or operations that reverse the resultsof the coding will be performed by a decoder.

Examples of a peripheral bus interface or a display interface mayinclude universal serial bus (USB) or high definition multimediainterface (HIDMI) or Displayport, and so on. Examples of storageinterfaces include serial advanced technology attachment (SATA),peripheral component interconnect (PCI), integrated drive electronics(IDE) interface, and the like. The techniques described in the presentdisclosure may be embodied in various electronic devices such as mobilephones, laptops, smartphones or other devices that are capable ofperforming digital data processing and/or video display.

FIG. 2 is a block diagram of a video processing apparatus 3600. Theapparatus 3600 may be used to implement one or more of the methodsdescribed herein. The apparatus 3600 may be embodied in a smartphone,tablet, computer, Internet of Things (IoT) receiver, and so on. Theapparatus 3600 may include one or more processors 3602, one or morememories 3604 and video processing hardware 3606. The processor(s) 3602may be configured to implement one or more methods described in thepresent disclosure. The memory (memories) 3604 may be used for storingdata and code used for implementing the methods and techniques describedherein. The video processing hardware 3606 may be used to implement, inhardware circuitry, some techniques described in the present disclosure.

FIG. 4 is a block diagram that illustrates an example video codingsystem 100 that may utilize the techniques of this disclosure.

As shown in FIG. 4 , video coding system 100 may include a source device110 and a destination device 120. Source device 110 generates encodedvideo data which may be referred to as a video encoding device.Destination device 120 may decode the encoded video data generated bysource device 110 which may be referred to as a video decoding device.

Source device 110 may include a video source 112, a video encoder 114,and an input/output (I/O) interface 116.

Video source 112 may include a source such as a video capture device, aninterface to receive video data from a video content provider, and/or acomputer graphics system for generating video data, or a combination ofsuch sources. The video data may comprise one or more pictures. Videoencoder 114 encodes the video data from video source 112 to generate abitstream. The bitstream may include a sequence of bits that form acoded representation of the video data. The bitstream may include codedpictures and associated data. The coded picture is a codedrepresentation of a picture. The associated data may include sequenceparameter sets, picture parameter sets, and other syntax structures. I/Ointerface 116 may include a modulator/demodulator (modem) and/or atransmitter. The encoded video data may be transmitted directly todestination device 120 via I/O interface 116 through network 130 a. Theencoded video data may also be stored onto a storage medium/server 130 bfor access by destination device 120.

Destination device 120 may include an I/O interface 126, a video decoder124, and a display device 122.

I/O interface 126 may include a receiver and/or a modem. I/O interface126 may acquire encoded video data from the source device 110 or thestorage medium/server 130 b. Video decoder 124 may decode the encodedvideo data. Display device 122 may display the decoded video data to auser. Display device 122 may be integrated with the destination device120, or may be external to destination device 120 which be configured tointerface with an external display device.

Video encoder 114 and video decoder 124 may operate according to a videocompression standard, such as the High Efficiency Video Coding (HEVC)standard, Versatile Video Coding (VVC) standard and other current and/orfurther standards.

FIG. 5 is a block diagram illustrating an example of video encoder 200,which may be video encoder 114 in the system 100 illustrated in FIG. 4 .

Video encoder 200 may be configured to perform any or all of thetechniques of this disclosure. In the example of FIG. 5 , video encoder200 includes a plurality of functional components. The techniquesdescribed in this disclosure may be shared among the various componentsof video encoder 200. In some examples, a processor may be configured toperform any or all of the techniques described in this disclosure.

The functional components of video encoder 200 may include a partitionunit 201, a prediction unit 202 which may include a mode select unit203, a motion estimation unit 204, a motion compensation unit 205 and anintra prediction unit 206, a residual generation unit 207, a transformunit 208, a quantization unit 209, an inverse quantization unit 210, aninverse transform unit 211, a reconstruction unit 212, a buffer 213, andan entropy encoding unit 214.

In other examples, video encoder 200 may include more, fewer, ordifferent functional components. In an example, prediction unit 202 mayinclude an intra block copy (IBC) unit. The IBC unit may performprediction in an IBC mode in which at least one reference picture is apicture where the current video block is located.

Furthermore, some components, such as motion estimation unit 204 andmotion compensation unit 205 may be highly integrated, but arerepresented in the example of FIG. 5 separately for purposes ofexplanation.

Partition unit 201 may partition a picture into one or more videoblocks. Video encoder 200 and video decoder 300 may support variousvideo block sizes.

Mode select unit 203 may select one of the coding modes, intra or inter,e.g., based on error results, and provide the resulting intra- orinter-coded block to a residual generation unit 207 to generate residualblock data and to a reconstruction unit 212 to reconstruct the encodedblock for use as a reference picture. In some example, Mode select unit203 may select a combination of intra and inter prediction (CIIP) modein which the prediction is based on an inter prediction signal and anintra prediction signal. Mode select unit 203 may also select aresolution for a motion vector (e.g., a sub-pixel or integer pixelprecision) for the block in the case of inter-prediction.

To perform inter prediction on a current video block, motion estimationunit 204 may generate motion information for the current video block bycomparing one or more reference frames from buffer 213 to the currentvideo block. Motion compensation unit 205 may determine a predictedvideo block for the current video block based on the motion informationand decoded samples of pictures from buffer 213 other than the pictureassociated with the current video block.

Motion estimation unit 204 and motion compensation unit 205 may performdifferent operations for a current video block, for example, dependingon whether the current video block is in an I slice, a P slice, or a Bslice.

In some examples, motion estimation unit 204 may perform uni-directionalprediction for the current video block, and motion estimation unit 204may search reference pictures of list 0 or list 1 for a reference videoblock for the current video block. Motion estimation unit 204 may thengenerate a reference index that indicates the reference picture in list0 or list 1 that contains the reference video block and a motion vectorthat indicates a spatial displacement between the current video blockand the reference video block. Motion estimation unit 204 may output thereference index, a prediction direction indicator, and the motion vectoras the motion information of the current video block. Motioncompensation unit 205 may generate the predicted video block of thecurrent block based on the reference video block indicated by the motioninformation of the current video block.

In other examples, motion estimation unit 204 may perform bi-directionalprediction for the current video block, motion estimation unit 204 maysearch the reference pictures in list 0 for a reference video block forthe current video block and may also search the reference pictures inlist 1 for another reference video block for the current video block.Motion estimation unit 204 may then generate reference indexes thatindicate the reference pictures in list 0 and list 1 containing thereference video blocks and motion vectors that indicate spatialdisplacements between the reference video blocks and the current videoblock. Motion estimation unit 204 may output the reference indexes andthe motion vectors of the current video block as the motion informationof the current video block. Motion compensation unit 205 may generatethe predicted video block of the current video block based on thereference video blocks indicated by the motion information of thecurrent video block.

In some examples, motion estimation unit 204 may output a full set ofmotion information for decoding processing of a decoder.

In some examples, motion estimation unit 204 may not output a full setof motion information for the current video. Rather, motion estimationunit 204 may signal the motion information of the current video blockwith reference to the motion information of another video block. Forexample, motion estimation unit 204 may determine that the motioninformation of the current video block is sufficiently similar to themotion information of a neighboring video block.

In one example, motion estimation unit 204 may indicate, in a syntaxstructure associated with the current video block, a value thatindicates to the video decoder 300 that the current video block has thesame motion information as another video block.

In another example, motion estimation unit 204 may identify, in a syntaxstructure associated with the current video block, another video blockand a motion vector difference (MVD). The motion vector differenceindicates a difference between the motion vector of the current videoblock and the motion vector of the indicated video block. The videodecoder 300 may use the motion vector of the indicated video block andthe motion vector difference to determine the motion vector of thecurrent video block.

As discussed above, video encoder 200 may predictively signal the motionvector. Two examples of predictive signaling techniques that may beimplemented by video encoder 200 include advanced motion vectorprediction (AMVP) and merge mode signaling.

Intra prediction unit 206 may perform intra prediction on the currentvideo block. When intra prediction unit 206 performs intra prediction onthe current video block, intra prediction unit 206 may generateprediction data for the current video block based on decoded samples ofother video blocks in the same picture. The prediction data for thecurrent video block may include a predicted video block and varioussyntax elements.

Residual generation unit 207 may generate residual data for the currentvideo block by subtracting (e.g., indicated by the minus sign) thepredicted video block(s) of the current video block from the currentvideo block. The residual data of the current video block may includeresidual video blocks that correspond to different sample components ofthe samples in the current video block.

In other examples, there may be no residual data for the current videoblock for the current video block, for example in a skip mode, andresidual generation unit 207 may not perform the subtracting operation.

Transform processing unit 208 may generate one or more transformcoefficient video blocks for the current video block by applying one ormore transforms to a residual video block associated with the currentvideo block.

After transform processing unit 208 generates a transform coefficientvideo block associated with the current video block, quantization unit209 may quantize the transform coefficient video block associated withthe current video block based on one or more quantization parameter (QP)values associated with the current video block.

Inverse quantization unit 210 and inverse transform unit 211 may applyinverse quantization and inverse transforms to the transform coefficientvideo block, respectively, to reconstruct a residual video block fromthe transform coefficient video block. Reconstruction unit 212 may addthe reconstructed residual video block to corresponding samples from oneor more predicted video blocks generated by the prediction unit 202 toproduce a reconstructed video block associated with the current blockfor storage in the buffer 213.

After reconstruction unit 212 reconstructs the video block, loopfiltering operation may be performed reduce video blocking artifacts inthe video block.

Entropy encoding unit 214 may receive data from other functionalcomponents of the video encoder 200. When entropy encoding unit 214receives the data, entropy encoding unit 214 may perform one or moreentropy encoding operations to generate entropy encoded data and outputa bitstream that includes the entropy encoded data.

FIG. 6 is a block diagram illustrating an example of video decoder 300which may be video decoder 124 in the system 100 illustrated in FIG. 4 .

The video decoder 300 may be configured to perform any or all of thetechniques of this disclosure. In the example of FIG. 6 , the videodecoder 300 includes a plurality of functional components. Thetechniques described in this disclosure may be shared among the variouscomponents of the video decoder 300. In some examples, a processor maybe configured to perform any or all of the techniques described in thisdisclosure.

In the example of FIG. 6 , video decoder 300 includes an entropydecoding unit 301, a motion compensation unit 302, an intra predictionunit 303, an inverse quantization unit 304, an inverse transformationunit 305, and a reconstruction unit 306 and a buffer 307. Video decoder300 may, in some examples, perform a decoding pass generally reciprocalto the encoding pass described with respect to video encoder 200 (FIG. 5).

Entropy decoding unit 301 may retrieve an encoded bitstream. The encodedbitstream may include entropy coded video data (e.g., encoded blocks ofvideo data). Entropy decoding unit 301 may decode the entropy codedvideo data, and from the entropy decoded video data, motion compensationunit 302 may determine motion information including motion vectors,motion vector precision, reference picture list indexes, and othermotion information. Motion compensation unit 302 may, for example,determine such information by performing the AMVP and merge mode.

Motion compensation unit 302 may produce motion compensated blocks,possibly performing interpolation based on interpolation filters.Identifiers for interpolation filters to be used with sub-pixelprecision may be included in the syntax elements.

Motion compensation unit 302 may use interpolation filters as used byvideo encoder 200 during encoding of the video block to calculateinterpolated values for sub-integer pixels of a reference block. Motioncompensation unit 302 may determine the interpolation filters used byvideo encoder 200 according to received syntax information and use theinterpolation filters to produce predictive blocks.

Motion compensation unit 302 may use some of the syntax information todetermine sizes of blocks used to encode frame(s) and/or slice(s) of theencoded video sequence, partition information that describes how eachmacroblock of a picture of the encoded video sequence is partitioned,modes indicating how each partition is encoded, one or more referenceframes (and reference frame lists) for each inter-encoded block, andother information to decode the encoded video sequence.

Intra prediction unit 303 may use intra prediction modes for examplereceived in the bitstream to form a prediction block from spatiallyadjacent blocks. Inverse quantization unit 303 inverse quantizes, i.e.,de-quantizes, the quantized video block coefficients provided in thebitstream and decoded by entropy decoding unit 301. Inverse transformunit 303 applies an inverse transform.

Reconstruction unit 306 may sum the residual blocks with thecorresponding prediction blocks generated by motion compensation unit302 or intra-prediction unit 303 to form decoded blocks. If desired, adeblocking filter may also be applied to filter the decoded blocks inorder to remove blockiness artifacts. The decoded video blocks are thenstored in buffer 307, which provides reference blocks for subsequentmotion compensation/intra prediction and also produces decoded video forpresentation on a display device.

A listing of clauses preferred by some embodiments is provided next.

The first set of clauses show example embodiments of techniquesdiscussed in the previous section. The following clauses show exampleembodiments of techniques discussed in the previous section (e.g., item1).

1. A video processing method (e.g., method 3000 shown in FIG. 3 ),comprising: performing (3002) a conversion between a video having one ormore chroma components, the video comprising one or more video picturescomprising one or more slices and a coded representation of the video,wherein the coded representation conforms to a format rule, wherein theformat rule specifies that a chroma array type field controls aconstraint on a conversion characteristic of chroma used during theconversion.

2. The method of clause 1, wherein the conversion characteristicincludes a constraint on a field indicative of presence of one or morescaling lists for the one or more chroma components.

3. The method of clause 1, wherein the conversion characteristicincludes a constraint on a value of a field indicative of a codewordused for signaling luma mapping with chroma scaling.

4. The method of clause 1, wherein the conversion characteristicincludes a constraint on values of syntax elements describing anadaptation parameter set for an adaptive loop filter used during theconversion.

5. The method of clause 1, wherein the format rule specifies to use asame semantics of one or more entries of an adaptation parameter set forthe chroma array type field signaling a 4:0:0 format or a separate colorcoding format.

6. The method of clause 5, wherein the one or more entries include anadaptive loop filter parameter or a scaling list parameter or a lumamapping with chroma scaling parameter.

7. The method of clauses 5-6, wherein the format rule further specifiesthat a constraint on the one or more entries of the adaptation parameterset is dependent on whether an identifier of the adaptation parameterset is included in the bitstream.

The following clauses show example embodiments of techniques discussedin the previous section (e.g., item 2).

8. A video processing method, comprising: performing a conversionbetween a video comprising one or more video pictures comprising one ormore video regions and a coded representation of the video, wherein thecoded representation conforms to a format rule that specifies theinclude a deblocking mode indicator for a video region indicative ofapplicability of a deblocking filter to the video region during theconversion.

9. The method of clause 8, wherein the deblocking mode indicator is an Nbit field where N is an integer greater than 1.

10. The method of any of clauses 8-9, wherein the deblocking modeindicator for the video region is included in a picture parameter set.

11. The method of clause 8, wherein the deblocking mode indicatorcorresponds to a flag included in a header of the video regionindicating applicability of the deblocking filter to the video region.

12. The method of any of clauses 8-11, wherein the format rule specifiesthat a flag that signals whether deblocking filter parameters signaledin the deblocking mode indicator are to override default parameters.

13. The method of any of clauses 8-12, wherein the video regioncorresponds to a video picture or a video slice.

The following clauses show example embodiments of techniques discussedin the previous section (e.g., item 3).

14. A video processing method, comprising: performing a conversionbetween a video comprising one or more video pictures comprising one ormore video slices and/or one or more video subpictures and a codedrepresentation of the video, wherein the coded representation conformsto a format rule that specifies that a flag indicating whether a singleslice per subpicture mode is deemed to be enabled for a video picture incase that a picture partitioning is disabled for the video picture.

The following clauses show example embodiments of techniques discussedin the previous section (e.g., item 4).

15. A video processing method, comprising: performing a conversionbetween a video comprising one or more video pictures comprising one ormore video slices and a coded representation of the video, wherein thecoded representation conforms to a format rule that specifies that apicture or a slice level chroma quantization parameter offset issignaled in a picture header or a slice header.

16. The method of clause 15, wherein the format rule specifies toinclude slice level chroma quantization parameter offsets in the sliceheader.

The following clauses show example embodiments of techniques discussedin the previous section (e.g., item 5).

17. A video processing method, comprising: performing a conversionbetween a video comprising one or more video pictures comprising one ormore video slices and a coded representation of the video, wherein thecoded representation conforms to a format rule that specifies that achroma quantization parameter (QP) table applicable for conversion of avideo block of the video is derived as an XOR operation between(delta_qp_in_val_minus1[i][j]+1) and delta_qp_diff_val[i][j], whereindelta_qp_in_val_minus1[i][j] specifies a delta value used to derive theinput coordinate of the j-th pivot point of the i-th chroma mappingtable and delta_qp_diff_val[i][j] specifies a delta value used to derivethe output coordinate of the j-th pivot point of the i-th chroma QPmapping table, where i and j are integers.

18. The method of any of clauses 1 to 17, wherein the conversioncomprises encoding the video into the coded representation.

19. The method of any of clauses 1 to 17, wherein the conversioncomprises decoding the coded representation to generate pixel values ofthe video.

20. A video decoding apparatus comprising a processor configured toimplement a method recited in one or more of clauses 1 to 19.

21. A video encoding apparatus comprising a processor configured toimplement a method recited in one or more of clauses 1 to 19.

22. A computer program product having computer code stored thereon, thecode, when executed by a processor, causes the processor to implement amethod recited in any of clauses 1 to 19.

23. A method, apparatus or system described in the present disclosure.

A second set of clauses show example embodiments of techniques discussedin the previous section (e.g., item 1 and 14 and 15).

1. A method of video processing (e.g., method 700 as shown in FIG. 7A),comprising: performing 702 a conversion between a video and a bitstreamof the video according to a format rule, and wherein the format rulespecifies that constraints on values of one or more first syntaxelements in an adaptation parameter set are defined based on semanticsof second syntax elements in a picture header and/or a slice header if apicture or a slice referring to the adaptation parameter set.

2. The method of clause 1, wherein the one or more first syntax elementsindicate a presence of a chroma information.

3. The method of clause 1, wherein the one or more first syntax elementsare used for indicating a presence of a chroma filter, chroma scalinglist, and/or LMCS (luma mapping with chroma scaling) residual scalingfactor information.

4. The method of clause 1, wherein the second syntax elements refer tothe adaptation parameter set.

5. The method of clause 1, wherein the format rule specifies that theconstraint on the value of a first syntax element is dependent on a typeof adaptation parameter set.

6. A method of video processing (e.g., method 710 as shown in FIG. 7B),comprising: performing 712 a conversion between a video and a bitstreamof the video according to a format rule, and wherein the format rulespecifies that a syntax element specifying whether a chroma-related APS(adaptation parameter set) syntax element is present is included in anAPS syntax structure.

7. The method of clause 6, wherein the format rule further specifiesthat the syntax element equal to 1 specifies that an APS (adaptationparameter set) NAL (network abstraction layer) unit is allowed toinclude chroma-related APS syntax element and the syntax element equalto 0 specifies that the APS NAL unit does not include chroma-related APSsyntax element.

8. The method of clause 6, wherein the syntax element is used to controla presence of other syntax elements in the adaptation parameter setand/or how to signal the other syntax elements and/or how to infervalues of the other syntax elements in case that the other syntaxelements are not present.

9. The method of clause 6, wherein the format rule specifies that thesyntax element equal to a first certain value specifies that thechroma-related APS syntax element is allowed to be present in the APS(adaptation parameter set) syntax structure that is a LMCS (luma mappingwith chroma scaling) data structure or a scaling data structure or a ALF(adaptive loop filtering) data structure.

10. The method of clause 6, wherein the format rule specifies that thesyntax element equal to a second certain value specifies that thechroma-related syntax element is not present in the APS (adaptationparameter set) syntax structure that is a LMCS (luma mapping with chromascaling) data structure or a scaling data structure or a ALF (adaptiveloop filtering) data structure.

11. The method of clause 6, wherein the format rule specifies, in casethat the syntax element equal to a certain value, that thechroma-related APS syntax element is not signalled in the APS(adaptation parameter set) syntax structure used for signaling adaptiveloop filtering information.

12. The method of clause 6, wherein the format rule specifies, in casethat the syntax element equal to a certain value, that thechroma-related APS syntax element is not signalled in the APS(adaptation parameter set) syntax structure used for signaling LMCS(luma mapping with chroma scaling) information.

13. The method of clause 6, wherein the format rule specifies, in casethat the syntax element equal to a certain value, that thechroma-related APS syntax element is not signalled in the APS(adaptation parameter set) syntax structure used for signaling scalinginformation.

14. The method of clause 13, wherein the chroma-related APS syntaxelement is scaling_list_copy_mode_flag[id],scaling_list_pred_id_delta[id], scaling_list_dc_coef[id−14],scaling_list_delta_coef[id][i], whereby id and i are integers.

15. The method of clause 14, wherein id is in a range between 0 and X,whereby X is a positive integer.

16. The method of clause 15, wherein id is not equal to X.

17. The method of clause 16, wherein X=27.

18. The method of clause 14, wherein id % M is not equal to N, whereby Mand N are integers.

19. The method of clause 18, wherein M=3, N=2.

20. The method of clause 6, wherein the format rule specifies, in casethat the chroma related syntax element is not present, a value of thechroma related syntax element is inferred to be equal to a certainvalue.

21. A method of video processing (e.g., method 720 as shown in FIG. 7C),comprising: performing 722 a conversion between a video and a bitstreamof the video according to a format rule, and wherein the format rulespecifies that a constraint on a value of a first syntax elementindicating a presence of chroma information in an APS (AdaptationParameter Set) NAL (Network Abstraction Layer) unit is based on a typeof the adaptation parameter set and a second syntax element indicating apresence of a chroma component in the video.

22. The method of clause 21, wherein the format rule further specifiesthat the constraint on the value of the first syntax element is derivedinformation included in a picture header or a slice header.

23. The method of clause 21, wherein the type of the adaptationparameter set is one of ALF (adaptive loop filter)_APS, SCAILING_APS, orLMCS (luma mapping with chroma scaling)_APS.

24. A method of video processing (e.g., method 730 as shown in FIG. 7D),comprising: performing 732 a conversion between a video and a bitstreamof the video according to a format rule, and wherein the format rulespecifies that a first syntax element indicating a presence of a chromacomponent in the video is constrained depending on a second syntaxelement indicating a presence of chroma information in an APS(Adaptation Parameter Set) NAL (Network Abstraction Layer) unit and/or atype of the APS.

25. The method of clause 24, wherein the type of the APS (AdaptationParameter Set) is one of ALF (adaptive loop filter)_APS, SCAILING_APS,or LMCS (luma mapping with chroma scaling)_APS.

26. A method of video processing (e.g., method 740 as shown in FIG. 7E),comprising: performing 742 a conversion between a video and a bitstreamof the video according to a format rule, and wherein the format rulespecifies, responsive to a second syntax element of an adaptationparameter set (APS) indicating a presence of a chroma component in thevideo being greater than a certain value, a value of a first syntaxelement of an APS NAL (Network Abstraction Layer) unit having an APSparameter type equal to LMCS (luma mapping with chroma scaling)_APS andan APS identifier equal to information included in a picture header of apicture referring to the APS is constrained to be equal to a certainvalue.

27. The method of clause 26, wherein the first syntax element indicatesa presence of chroma information in the APS NAL unit.

28. A method of video processing (e.g., method 750 as shown in FIG. 7F),comprising: performing a conversion between a video and a bitstream ofthe video according to a format rule, and wherein the format rulespecifies how to signal or constrain one or more first syntax elementsin an adaptation parameter set based on a value of a APS (adaptationparameter set) syntax element specifying an allowance of presence ofchroma-related syntax elements in an adaptation parameter set.

29. The method of clause 28, wherein the one or more first syntaxelements include a first syntax element indicative of whether a chromafilter is signalled, a second syntax element indicative of whethercross-component filters for a Cb colour component is signalled, and/or athird syntax element indicative of whether cross-component filters for aCr colour component is signalled.

30. The method of clause 29, wherein the format rule specifies to set arequirement that at least one of the first syntax elements, the secondsyntax element, or the third syntax element is equal to 1 in case thatthe APS (adaptation parameter set) syntax element specifies that thechroma-related syntax elements are allowed to be present.

31. The method of clause 29, wherein the one or more first syntaxelements include a first syntax element indicative of whether a chromafilter is signalled and a second syntax element whether cross-componentfilters for a Cb colour component or a Cr colour component aresignalled.

32. The method of clause 31, wherein the format rule specifies to set arequirement that at least one of the first syntax element or the secondsyntax element is equal to 1 in case that the APS (adaptation parameterset) syntax element specifies that the chroma-related syntax elementsare allowed to be present.

33. The method of clause 28, wherein the format rule specifies that apresence of a first syntax element in the adaptation parameter set isdependent on values of one or more other syntax elements in theadaptation parameter set in case that that the APS (adaptation parameterset) syntax element specifies that the chroma-related syntax elementsare allowed to be present.

34. The method of clause 33, wherein the first syntax element indicateswhether a chroma filter is signalled, and the one or more other syntaxelements include a second syntax element indicative of whethercross-component filters for a Cb colour component is signalled and/or athird syntax element indicative of whether cross-component filters for aCr colour component is signalled.

35. The method of clause 33, wherein the first syntax element indicateswhether cross-component filters for a Cb colour component is signalled,and the one or more other syntax elements include a second syntaxelement indicative of whether a chroma filter is signalled and/or athird syntax element indicative of whether cross-component filters for aCr colour component is signalled.

36. The method of clause 33, wherein the first syntax element indicateswhether cross-component filters for a Cr colour component is signalled,and the one or more other syntax elements include a second syntaxelement indicative of whether a chroma filter is signalled and/or athird syntax element indicative of whether cross-component filters for aCb colour component is signalled.

37. The method of clause 33, wherein the first syntax element indicateswhether a chroma filter is signalled and the one or more other syntaxelements include a second syntax element indicating whethercross-component filters for a Cb colour component or a Cr colourcomponent are signalled.

38. The method of clause 33, wherein the first syntax element indicateswhether cross-component filters for a Cb colour component or a Cr colourcomponent or both Cb and Cr colour components are signalled and the oneor more other syntax elements include a second syntax element indicativeof whether a chroma filter is signalled.

39. The method of clause 33, wherein the format rule specifies, in casethat the values of the one or more other second syntax elements areequal to 0, to omit the first syntax element.

40. The method of clause 33, wherein the format rule specifies, in casethat the first syntax element is not present, that a value of the firstsyntax element is inferred to be equal to a certain value.

41. The method of clause 33, wherein the format rule specifies that avalue of the first syntax element is inferred to be equal to a certainvalue based on whether the APS (adaptation parameter set) syntax elementspecifies that the chroma-related syntax elements are allowed to bepresent.

42. A method of video processing (e.g., method 760 as shown in FIG. 7G),comprising: performing 762 a conversion between a video and a bitstreamof the video according to a format rule, and wherein the format rulespecifies that an ALF (adaptive loop filter) APS (adaptation parameterset) includes a first syntax element indicating a presence of chromafiltering information.

43. The method of clause 42, wherein the format rule further specifiessignalling of a second syntax elements is based on a value of the firstsyntax element.

44. The method of clause 43, wherein the format rule specifies, in casethat the first syntax element indicates that the chroma filteringinformation is not present, the signalling of a second syntax elementthat indicates luma filter information is skipped.

45. The method of clause 44, wherein the format rule specifies, in casethat the second syntax element is not present, a value of the secondsyntax element is inferred to be a certain value.

46. The method of clause 42, wherein the format rule specifies, in casethat the first syntax element indicates that the chroma filteringinformation is present, at least one of an indication indicating apresence of at least one of a chroma filter or a cross-component filterfor a Cr colour component or a Cb colour component is set to a certainvalue.

47. The method of clause 46, wherein the indication indicates thepresence of the cross-component filters for the Cr colour component andthe Cb colour component.

48. The method of any of clauses 1 to 47, wherein the conversionincludes encoding the video into the bitstream.

49. The method of any of clauses 1 to 47, wherein the conversionincludes decoding the video from the bitstream.

50. The method of clauses 1 to 47, wherein the conversion includesgenerating the bitstream from the video, and the method furthercomprises: storing the bitstream in a non-transitory computer-readablerecording medium.

51. A video processing apparatus comprising a processor configured toimplement a method recited in any one or more of clauses 1 to 50.

52. A method of storing a bitstream of a video, comprising, a methodrecited in any one of clauses 1 to 50, and further including storing thebitstream to a non-transitory computer-readable recording medium.

53. A computer readable medium storing program code that, when executed,causes a processor to implement a method recited in any one or more ofclauses 1 to 50.

54. A computer readable medium that stores a bitstream generatedaccording to any of the above described methods.

55. A video processing apparatus for storing a bitstream representation,wherein the video processing apparatus is configured to implement amethod recited in any one or more of clauses 1 to 50.

In the present disclosure, the term “video processing” may refer tovideo encoding, video decoding, video compression or videodecompression. For example, video compression algorithms may be appliedduring conversion from pixel representation of a video to acorresponding bitstream representation or vice versa. The bitstreamrepresentation of a current video block may, for example, correspond tobits that are either co-located or spread in different places within thebitstream, as is defined by the syntax. For example, a macroblock may beencoded in terms of transformed and coded error residual values and alsousing bits in headers and other fields in the bitstream. Furthermore,during conversion, a decoder may parse a bitstream with the knowledgethat some fields may be present, or absent, based on the determination,as is described in the above solutions. Similarly, an encoder maydetermine that certain syntax fields are or are not to be included andgenerate the coded representation accordingly by including or excludingthe syntax fields from the coded representation.

The disclosed and other solutions, examples, embodiments, modules andthe functional operations described in this document can be implementedin digital electronic circuitry, or in computer software, firmware, orhardware, including the structures disclosed in this document and theirstructural equivalents, or in combinations of one or more of them. Thedisclosed and other embodiments can be implemented as one or morecomputer program products, i.e., one or more modules of computer programinstructions encoded on a computer readable medium for execution by, orto control the operation of, data processing apparatus. The computerreadable medium can be a machine-readable storage device, amachine-readable storage substrate, a memory device, a composition ofmatter effecting a machine-readable propagated signal, or a combinationof one or more them. The term “data processing apparatus” encompassesall apparatus, devices, and machines for processing data, including byway of example a programmable processor, a computer, or multipleprocessors or computers. The apparatus can include, in addition tohardware, code that creates an execution environment for the computerprogram in question, e.g., code that constitutes processor firmware, aprotocol stack, a database management system, an operating system, or acombination of one or more of them. A propagated signal is anartificially generated signal, e.g., a machine-generated electrical,optical, or electromagnetic signal, that is generated to encodeinformation for transmission to suitable receiver apparatus.

A computer program (also known as a program, software, softwareapplication, script, or code) can be written in any form of programminglanguage, including compiled or interpreted languages, and it can bedeployed in any form, including as a stand-alone program or as a module,component, subroutine, or other unit suitable for use in a computingenvironment. A computer program does not necessarily correspond to afile in a file system. A program can be stored in a portion of a filethat holds other programs or data (e.g., one or more scripts stored in amarkup language document), in a single file dedicated to the program inquestion, or in multiple coordinated files (e.g., files that store oneor more modules, sub programs, or portions of code). A computer programcan be deployed to be executed on one computer or on multiple computersthat are located at one site or distributed across multiple sites andinterconnected by a communication network.

The processes and logic flows described in this document can beperformed by one or more programmable processors executing one or morecomputer programs to perform functions by operating on input data andgenerating output. The processes and logic flows can also be performedby, and apparatus can also be implemented as, special purpose logiccircuitry, e.g., a field programmable gate array (FPGA) or anapplication specific integrated circuit (ASIC).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read only memory ora random-access memory or both. The essential elements of a computer area processor for performing instructions and one or more memory devicesfor storing instructions and data. Generally, a computer will alsoinclude, or be operatively coupled to receive data from or transfer datato, or both, one or more mass storage devices for storing data, e.g.,magnetic, magneto optical disks, or optical disks. However, a computerneed not have such devices. Computer readable media suitable for storingcomputer program instructions and data include all forms of non-volatilememory, media and memory devices, including by way of examplesemiconductor memory devices, e.g., erasable programmable read-onlymemory (EPROM), electrically erasable programmable read-only memory(EEPROM), and flash memory devices; magnetic disks, e.g., internal harddisks or removable disks; magneto optical disks; and compact disc,read-only memory (CD ROM) and digital versatile disc read-only memory(DVD-ROM) disks. The processor and the memory can be supplemented by, orincorporated in, special purpose logic circuitry.

While the present disclosure contains many specifics, these should notbe construed as limitations on the scope of any subject matter or ofwhat may be claimed, but rather as descriptions of features that may bespecific to particular embodiments of particular techniques. Certainfeatures that are described in the present disclosure in the context ofseparate embodiments can also be implemented in combination in a singleembodiment. Conversely, various features that are described in thecontext of a single embodiment can also be implemented in multipleembodiments separately or in any suitable subcombination. Moreover,although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. Moreover, the separation of various system components in theembodiments described in the present disclosure should not be understoodas requiring such separation in all embodiments.

Only a few implementations and examples are described and otherimplementations, enhancements and variations can be made based on whatis described and illustrated in the present disclosure.

1. A method of video processing, comprising: performing a conversionbetween a video and a bitstream of the video according to a format rule,and wherein the format rule specifies that a first syntax elementspecifying whether one or more chroma-related adaptation parameter set(APS) syntax elements are present in an APS syntax structure is includedin the APS syntax structure, wherein the first syntax element equal to 1specifies that an APS network abstraction layer (NAL) unit is allowed toinclude the one or more chroma-related APS syntax elements and the firstsyntax element equal to 0 specifies that the APS NAL unit does notinclude the one or more chroma-related APS syntax elements, wherein theAPS NAL unit has APS parameters type equal to scaling list APS type,luma mapping with chroma scaling (LMCS) APS type, or adaptive loopfiltering (ALF) APS type, and the one or more chroma-related APS syntaxelements include scaling list chroma-related data syntax elements, LMCSchroma-related data syntax elements, or ALF chroma-related data syntaxelements, and wherein constraints on value of the first syntax elementin different APS parameters types are different, wherein a one-wayconstraint of the first syntax element in the APS NAL unit with thescaling list APS type is applied and two-way constraints of the firstsyntax element in the APS NAL unit with the LMCS APS type or the ALF APStype are applied.
 2. The method of claim 1, wherein the one-wayconstraint specifies if a first certain condition is true, a firstconstraint of the first syntax element is applied, the two-wayconstraints specify if the first certain condition is true, the firstconstraint of the first syntax element is applied, otherwise a secondconstraint of the first syntax element is applied.
 3. The method ofclaim 2, wherein the one-way constraint or the two-way constraints ofthe first syntax element are based on a chroma format index.
 4. Themethod of claim 1, wherein when i) the APS NAL unit has the APSparameters type equal to the scaling list APS type, ii) the first syntaxelement is equal to 0, iii) a variable id is not equal to X and id % Mis not equal to N, the scaling list chroma-related data syntax elementsare excluded from the APS syntax structure, whereby X, M and N areintegers.
 5. The method of claim 4, wherein X=27.
 6. The method of claim4, wherein M=3, N=2.
 7. The method of claim 1, wherein when the APS NALunit has the APS parameters type equal to the ALF APS type and the firstsyntax element is equal to 0, the ALF chroma-related data syntaxelements are excluded from the APS syntax structure.
 8. The method ofclaim 1, wherein when the APS NAL unit has the APS parameters type equalto the LMCS APS type and the first syntax element is equal to 0, theLMCS chroma-related data syntax elements are excluded from the APSsyntax structure.
 9. The method of claim 1, wherein the conversionincludes encoding the video into the bitstream.
 10. The method of claim1, wherein the conversion includes decoding the video from thebitstream.
 11. An apparatus for processing video data comprising aprocessor and a non-transitory memory with instructions thereon, whereinthe instructions upon execution by the processor, cause the processorto: perform a conversion between a video and a bitstream of the videoaccording to a format rule, wherein the format rule specifies that afirst syntax element specifying whether one or more chroma-relatedadaptation parameter set (APS) syntax elements are present in an APSsyntax structure is included in the APS syntax structure, wherein thefirst syntax element equal to 1 specifies that an APS networkabstraction layer (NAL) unit is allowed to include the one or morechroma-related APS syntax elements and the first syntax element equal to0 specifies that the APS NAL unit does not include the one or morechroma-related APS syntax elements, wherein the APS NAL unit has APSparameters type equal to scaling list APS type, luma mapping with chromascaling (LMCS) APS type, or adaptive loop filtering (ALF) APS type, andthe one or more chroma-related APS syntax elements include scaling listchroma-related data syntax elements, LMCS chroma-related data syntaxelements, or ALF chroma-related data syntax elements, and whereinconstraints on value of the first syntax element in different APSparameters types are different, wherein a one-way constraint of thefirst syntax element in the APS NAL unit with the scaling list APS typeis applied and two-way constraints of the first syntax element in theAPS NAL unit with the LMCS APS type or the ALF APS type are applied. 12.The apparatus of claim 11, wherein the one-way constraint specifies if afirst certain condition is true, a first constraint of the first syntaxelement is applied; the two-way constraints specify if the first certaincondition is true, the first constraint of the first syntax element isapplied, otherwise a second constraint of the first syntax element isapplied, and wherein the one-way constraint or the two-way constraintsof the first syntax element are based on a chroma format index.
 13. Theapparatus of claim 11, wherein when i) the APS NAL unit has the APSparameters type equal to the scaling list APS type, ii) the first syntaxelement is equal to 0, iii) a variable id is not equal to X and id % Mis not equal to N, the scaling list chroma-related data syntax elementsare excluded from the APS syntax structure, whereby X, M and N areintegers, and wherein X=27, M=3, and N=2.
 14. The apparatus of claim 11,wherein when the APS NAL unit has the APS parameters type equal to theALF APS type and the first syntax element is equal to 0, the ALFchroma-related data syntax elements are excluded from the APS syntaxstructure.
 15. The apparatus of claim 11, wherein when the APS NAL unithas the APS parameters type equal to the LMCS APS type and the firstsyntax element is equal to 0, the LMCS chroma-related data syntaxelements are excluded from the APS syntax structure.
 16. Anon-transitory computer-readable storage medium storing instructionsthat cause a processor to: perform a conversion between a video and abitstream of the video according to a format rule, wherein the formatrule specifies that a first syntax element specifying whether one ormore chroma-related adaptation parameter set (APS) syntax elements arepresent in an APS syntax structure is included in the APS syntaxstructure, wherein the first syntax element equal to 1 specifies that anAPS network abstraction layer (NAL) unit is allowed to include the oneor more chroma-related APS syntax elements and the first syntax elementequal to 0 specifies that the APS NAL unit does not include the one ormore chroma-related APS syntax elements, wherein the APS NAL unit hasAPS parameters type equal to scaling list APS type, luma mapping withchroma scaling (LMCS) APS type, or adaptive loop filtering (ALF) APStype, and the one or more chroma-related APS syntax elements includescaling list chroma-related data syntax elements, LMCS chroma-relateddata syntax elements, or ALF chroma-related data syntax elements, andwherein constraints on value of the first syntax element in differentAPS parameters types are different, wherein a one-way constraint of thefirst syntax element in the APS NAL unit with the scaling list APS typeis applied and two-way constraints of the first syntax element in theAPS NAL unit with the LMCS APS type or the ALF APS type are applied. 17.The non-transitory computer-readable storage medium of claim 16, whereinthe one-way constraint specifies if a first certain condition is true, afirst constraint of the first syntax element is applied; the two-wayconstraints specify if the first certain condition is true, the firstconstraint of the first syntax element is applied, otherwise a secondconstraint of the first syntax element is applied, and wherein theone-way constraint or the two-way constraints of the first syntaxelement are based on a chroma format index.
 18. The non-transitorycomputer-readable storage medium of claim 16, wherein when i) the APSNAL unit has the APS parameters type equal to the scaling list APS type,ii) the first syntax element is equal to 0, iii) a variable id is notequal to X and id % M is not equal to N, the scaling list chroma-relateddata syntax elements are excluded from the APS syntax structure, wherebyX, M and N are integers, and wherein X=27, M=3, and N=2.
 19. Anon-transitory computer-readable recording medium storing a bitstream ofa video which is generated by a method performed by a video processingapparatus, wherein the method comprises: generating the bitstream of thevideo according to a format rule, and wherein the format rule specifiesthat a first syntax element specifying whether one or morechroma-related adaptation parameter set (APS) syntax elements arepresent in an APS syntax structure is included in the APS syntaxstructure, wherein the first syntax element equal to 1 specifies that anAPS network abstraction layer (NAL) unit is allowed to include the oneor more chroma-related APS syntax elements and the first syntax elementequal to 0 specifies that the APS NAL unit does not include the one ormore chroma-related APS syntax elements, wherein the APS NAL unit hasAPS parameters type equal to scaling list APS type, luma mapping withchroma scaling (LMCS) APS type, or adaptive loop filtering (ALF) APStype, and the one or more chroma-related APS syntax elements includescaling list chroma-related data syntax elements, LMCS chroma-relateddata syntax elements, or ALF chroma-related data syntax elements, andwherein constraints on value of the first syntax element in differentAPS parameters types are different, wherein a one-way constraint of thefirst syntax element in the APS NAL unit with the scaling list APS typeis applied and two-way constraints of the first syntax element in theAPS NAL unit with the LMCS APS type or the ALF APS type are applied. 20.The non-transitory computer-readable recording medium of claim 19,wherein the one-way constraint specifies if a first certain condition istrue, a first constraint of the first syntax element is applied; thetwo-way constraints specify if the first certain condition is true, thefirst constraint of the first syntax element is applied, otherwise asecond constraint of the first syntax element is applied, and whereinthe one-way constraint or the two-way constraints of the first syntaxelement are based on a chroma format index.